Absurdly Sharp Blade



""The Sword of Heroes! Said to be so sharp you can cut yourself just by looking at--Oww!""

- Po, Kung Fu Panda

An absurdly sharp blade is a bladed weapon with Absurd Cutting Power because it's just that damn sharp. No magic, technology, superpowers, or other type of Applied Phlebotinum required to slice and dice to your heart's content. Such things may have been involved in the production of the blade, but when in use, its cutting power comes from its pure physical sharpness alone.

Blades like these almost always result in a Clean Cut -- in fact, about the only thing they can't cut is a similarly sharp weapon. Expect to hear some Audible Sharpness (Audible Gleam optional) whenever one of these blades is in use. Frequently used in Single Stroke Battles.

Sharpened to A Single Atom is a subtrope popular in Sci Fi settings, where the blade is so sharp that the width of the cutting edge can be measured in atoms or molecules.

Advertising

 * The So Bad Its Good ads for Ginsu knives try to sell the Ginsu 2000 as an Absurdly Sharp Blade that Never Needs Sharpening. Though it's a Deceptively Simple Demonstration, as cutting through an aluminum can (or whatever absurdly hard object they demonstrate the knife slicing through) is a lot easier than many everyday cooking tasks, such as slicing through a winter squash, clearing beef gristle, or boning a fish fillet.
 * "If you really need a knife that can cut through a shoe, maybe you're not buying the best quality meat."
 * Chef Tony once advertised the Perfection Series knives as so sharp they can cut a pineapple in half in midair.

Anime and Manga

 * Integra Hellsing manages to deeply stab herself in the finger with a butter knife.
 * In Fullmetal Alchemist, the homunculus Lust's "ultimate lance" ability extends her fingers into long blades which can cut perfectly cleanly through anything, even though they are clearly 3/4 of an inch thick for most of their length.
 * Pride's shadows can cut or pierce just about anything - and under normal lighting conditions, they can reach just about anywhere.
 * In Grenadier - The Smiling Senshi, the hero, a swordsman, has a(n impractically) long katana, sharp enough to slice an incoming artillery shell in half (without triggering the fuse), and cut a giant boulder clean in half, albeit with assistance from the heroine's pistol (four rounds to the back of the blade at the moment of contact, to propel it into the rock).
 * Goemon, from Lupin the Third, regularly slices through things like airplanes and buildings with his katana, the Zantetsuken ("Iron-Cutting Sword")-- or in the manga, Nagareboshi ("Falling Star"). Episode Zero: First Contact and Dragon of Doom both explain that the Zantetsuken is made out of a mysterious alloy (in the manga, it's said to be made of a rare steel alloy produced from meteoric iron) that is almost indestructible, though apparently the metal can cut itself. Episode Zero finds Goemon wanting to destroy the formula for the alloy since he doesn't want to risk another Zantetsuken being made, rendering his own vulnerable.
 * Played with in one episode of the second series, when someone steals Zantetsuken and attaches it to a remote-controlled airplane which can slice up tanks and other planes by flying into them. Apparently, the only thing it can't cut is konnyaku gel, which the gang uses to finally stop the flying sword.
 * In Saint Seiya, Shura's Excalibur (the strongest weapon of the saints, which can cut through anything, be it flesh, armor, attacks or dimensions) consists of.... his limbs, most frequently his arm. Yes, it is imbued with cosmos, but it's still an arm.
 * Ax Crazy Sword Guy from the first episode of New Getter Robo has this going on with his katana. Including slicing down the better part of a Shinto Shrine. It works for Ryoma when he disarms him too; he grabs it, redirects into the face of one of his attackers, slashes the sword's owner with it, and then hurls it through the arm of the Knife Nut. There's a pause of about two seconds before his arm goes off and blood starts spewing everywhere.
 * This fight was taken almost frame-for-frame from Ken Ishikawa's original Getter Robo manga, with the major exception that instead of Adult Ryoma, it was the classic version who did it.
 * Subverted by the Z-Sword in Dragonball Z. They think the reason it's legendary is because it's impossibly sharp and unbreakable, but it turns out to be something else entirely.
 * Yajirobe's katana, however, is ridiculously sharp. Weapons are mostly useless against even weak enemies, in DBZ. But Yajirobe is able to, despite his unimpressive strength (by DBZ standards), slice off Oozaru Vegeta's gigantic tail in a single swing.
 * Also averted with Trunks' sword, which, although it can apparently easily cut through anything weaker than its wielder, is broken...against #18's arm.
 * Played with in Slayers with the Blast Sword. It was so sharp you couldn't put it in a sheath without cutting it in half. It was so sharp it was useless so they had to find someone to cast some magic on it to dull the blade. But even the dulled blade still fits this trope.
 * Samurai swords in Samurai Seven can cut through mechas and FLYING BATTLESHIPS in seemingly one strike, and it seems that the only thing that wouldn't get cut in half by them are other samurai swords.
 * This one seems like it has more to do with the swordsman than the sword, making it less of Absurdly Sharp Blade and more of Charles Atlas Superpower
 * Setsuna of Mahou Sensei Negima has one of these. In a recent chapter she slices a giant iron ball in half without even noticing, and during her fight with Evangeline in the Tournament Arc she slices a giant ball of ice in half... with the back of the blade.
 * Mihawk of One Piece sliced off the top half of a frozen wave twice as high as the island he was on. He was about a kilometer or so away at the moment, and it was a missed slash aimed at Luffy.
 * All swordsmen in One Piece have this to an extent. However, the mark of a really skilled swordsmen(and the only way to learn how to cut steel) is the ability to invert this; that is, learn how to "cut nothing", which basically involves being able to slash at something without harming it if the swordsman doesn't actually want to harm it. This is demonstrated by Zoro, who slashes through a group of leaves without so much as scratching any of them, and Zoro's sensei, who shows Zoro how its done in a flashback by swinging his sword into a sheet of paper without damaging it.
 * As seen above, any of the weapons that Shigure uses in Kenichi the Mightiest Disciple will probably be absurdly sharp. That means ANYTHING from wooden spoons to plastic sword controllers.
 * This is parodied Yonkoma-style in an Omake (seen in the 2nd anime ending: She sharpens a kitchen knife for Miu, which ends up cutting through the radish, cutting board, and about three feet of counter/cabinet.
 * Darker Than Black: If Hei's knives aren't these, then crappy concrete is probably more of a threat to Japan than Hell's Gate and everything that came out of it put together.
 * In Until Death Do Us Part, the protagonist's sword is camouflaged inside his white cane. Said sword is able to cut through a gun... And the cut is so clean they actually manage to stick the parts of the gun back together.
 * Shizuru's power in the light novel Mai-HiME Destiny is to make any sword into this. Naturally, it works better with katanas.
 * While Samurai Champloo contains more typical examples with swords, the blade on Umanosuke's kusarigama really takes the cake, being able to cut clear through rocks and thick wooden support beams without even slowing down. It also makes such an insanely loud noise when swung through the air that you'd think it's regularly breaking the sound barrier. Ultimately, this ends up completely biting him in the ass, as Mugen is able to swing the blade back at him and even without a huge amount of force behind it the thing manages to cut his head off.
 * Rurouni Kenshin is guilty of this. Sagara Sanosuke may have a BFS but Kenshin's original sword cut through it. He's also used the sharp side of his reverse-blade sword to slice through cannonballs and a huge lamp-post.
 * When his original reverse blade sword broke, he went to visit a swordmaker. That man's cutting knives (as in for cooking) were able to slice a turnip in half with a cut so fine that Kenshin was able to fit the two halves back together without showing a seam.
 * Justified with Cardcaptor Sakura's Sword card; its cutting power depends on the will of the user, meaning that if somebody using the sword wanted it to, it could even slice through rock.
 * Mai in Kanon has a sword that's strong enough to slice clean through several metal objects around her and crush a brick wall.
 * The Blade of Masane Amaha's Witchblade in the anime, as demonstrated multiple times as it takes machines a while to realize that they have been cut and explode.
 * Every katana forged by Luke in The Sacred Blacksmith seems to be capable of cutting through most things, such as a two handed sword or another katana that was swung at it, meaning it can cut through other swords with no force behind it at all. His magically forged katanas are offset by their fragility, but they still cut through the insanely overpowered demon swords.
 * In his first episode on F-Zero: GP Legend, Samurai Goroh uses his sword to cut through prison bars, a missile flying towards him (while on the back of a moving vehicle), an armored vehicle, and at the end, an -entire spaceship-. Truly Goroh's blade is the mightiest force in the universe.
 * In Toriko, kitchen knives made by the master sharpener Melk can't be bought without a license, to prevent unskilled users from accidentally injuring themselves. This culminates in what could possibly be the best example of this trope, when Melk the 2nd completes Komatsu's new knife. A light swing of it proceeds to make a gigantic gash in the mountain. It didn't come in contact with anything.
 * In Panty and Stocking With Garterbelt, Stocking's katana can slice through an entire semi-truck.
 * Macross Frontier's Brera Sterne has a Blade Below the Shoulder no larger than a small combat knife that cuts a Hydra in half. While the setting could have Applied Phlebotinum, such as the Pin Point Barrier knives on the Transforming Mecha, but no explanation or even visual/audio cue is ever given for Brera's knife other than it cuts tiger-sized creatures in half.
 * Fist of the North Star. Those who practice Hokuto Shinken have a Finger Poke of Doom, but practitioners of Nantou Seiken like Rei specialize in a fighting style that creates a cutting force at the tips of his fingers. He has Absurdly Sharp Fingers. He cuts enemies apart by making simple slashing or clawing motions at them, sometimes from a distance. This is how Shin punched those seven scars into Kenshiro with his fingers in the first place.
 * In Zoids, if it's a blade at all chances are there's nothing it can't cut through.
 * Many swords in Yaiba are really, really sharp. Justified, because they're magical.
 * The swords given to the warriors in the unnamed organization in Claymore. This is lampshaded at one point when Miria says something along the lines of "Have you ever wondered why our swords never chip or dull, no matter how hard we swing or how hard the surface we hit? What exactly are they made of? The material can't be from this continent (all that she knows of the world is her own continent) and I've looked everywhere."
 * The sword Melan wields in Brigadoon Marin and Melan can cut through almost anything on earth, including bullets and gun barrels. However, it's not always successful against weapons made on Brigadoon.
 * Solomon Goldsmith's from Blood Plus has a Blade Below the Shoulder capable of cutting through cliffs and the limbs of Chevaliers. This includes the arm of  who sports extremely powerful.
 * Micaiah's katana in Magical Girl Lyrical Nanoha Vi Vid, which is mentioned to be a normal physical sword. After she sharpened it for the tournament, she tests its edge by slicing a falling bus into fours.
 * The Gerbera Straight used by Lowe Guele's Gundam Astray Red Frame. He had it built because he needed a weapon to defend himself with, beam sabers drained precious energy and a GINN's Heavy Sword used inertia, thus precious energy, to cut.
 * Gundam 00 has the GN Swords (any variety except Beam Swords). They are all quite bulky, but they are absurdly sharp despite not looking like it. Justified in-universe as GN Particles can (apparently) be used to increase a solid blade's sharpness. Don't ask, it doesn't even make sense in context.
 * Gintama has something of a subversion. Sakata Gintoki's sword is so sharp it can be used to cut through several feet of metal. It's also made of wood.
 * Creed Diskenth's ki blade in Black Cat will slice cleanly through everything short of the orichalcum used in Chronos assassins' weapons. When he cuts off Train's hand during their first encounter in the manga, the doctor who reattaches said hand notes that it's as if the cells were simply pulled apart.

Comic Books

 * Nemesis, a member (and former enemy) of Alpha Flight, uses a saber whose blade is only a single molecule wide.
 * Wolverine from the X-Men has adamantium claws in his hands. There are very few things that they can't cut.
 * Frequent Wolverine foe Silver Samurai generates a tachyon field around whatever he touches (typically his heirloom sword), allowing him to cut through anything except-- you guessed it-- adamantium.
 * The Libra killer in Top Ten did this. In reality, she was an alien in a volatile life stage, with atom-slicing filaments coming from her body.
 * The super-powered serial killer in ~H-E-R-O~ used one of these, thanks to his superpower being the ability to use any superpower he could think of. He just selected "the power to cut through anything".
 * In Camelot 3000, King Arthur causes a nuclear explosion by cutting an atom on the point of Excalibur. Earlier in the story, Arthur notes that Excalibur's powers are not confined to destruction, and shoving the sword into fuel cells is enough to bring them to full power.
 * In Legion of Super-Heroes, the Persuader's Atomic Axe can cut through anything, including the force of gravity.
 * The Vorpal Blade wielded by Boy Blue in Fables. It's so sharp that the only time it didn't cut right through a target is because the target was the Big Bad, who has placed countless millions of protection spells on himself over the years.
 * In DC Comics, a sharpened blade coated with "lubrilon" is so slick it can cut through anything with almost no friction.
 * Vandal Savage's illegal Omicronian Knife Suit from DC One Million. It used Nanomachines to constantly sharpen the blades so they could "cut out your very soul".
 * In the New Gods series, Giliotina's swords can slice through anything. Then again, she doesn't really need them.
 * Mack "Clownface" Delgado from Body Bags. He's a Badass Knife Nut who is seen cutting two men in half with one diagonal stroke among other impressive feats.
 * In Scott Pilgrim, Knives Chau's father has a sword so sharp it can cut clean through a streetcar!
 * Warblade of the WildC.A.T.s can fashion parts of his body to make blades as sharp as he wants. How sharp? Sharp enough to cut the Nigh Invulnerable Captain Atom.
 * Hawk And Dove villain Kestrel has claws that cut through anything, including reality. In one alternate future, the heroes' child inherits this power and uses it for impromptu brain surgery, to literally correct a supervillain's way of thinking. She does it through his Powered Armor.
 * Sin City's Miho has blades that are sharp enough to slice right through human bone or, in one case, a car roof.
 * In World of Warcraft manga comics there is a tale of a dwarven blacksmith. He is regarded as the best weaponsmith in the world. After his son is killed by one of his weapons he forges the best weapon he has ever crafted for the purpose to avenge his son. To test his blade he he destroys his own anvil with a single one-handed strike.

Film

 * Transformers: Revenge of the Fallen had Reedman, a robot sharp enough that it cut a soldier in half just through a full-body tackle.
 * In Stargate Continuum, the blade held by Ba'al (and stolen by Qetesh) has an edge "only one atom thick", enough to cut Ba'al clean in half.
 * The Hattori Hanzo katana owned by the Bride in Kill Bill. "I can tell you with no ego, this is my finest sword. If on your journey, you should encounter God, God will be cut." This is a quote of Musashi, although in his context it meant steeling yourself for battle no matter who faced you.
 * At the end of Underworld,
 * Shortly after Logan receives his adamantium infusion in X Men Origins Wolverine, he slices up several items in a farmhouse bathroom (including a porcelain sink) with his now impossibly sharp claws, despite applying what appears to be no more than the force required to move an unrestrained arm.
 * The legendary Green Destiny sword in Crouching Tiger Hidden Dragon is capable of slicing through virtually any other weapon, and apparently never gets chipped or cracked, regardless of how often it gets used. Amusingly, in one of the later fight scenes there is a blink-and-you'll-miss-it shot that clearly shows the prop sword to have been severely deformed in the action sequence.
 * In Equilibrium, Despite the fact that whatever the edge is like, the blade is thick enough that this could not possibly happen.
 * In Clash of the Titans, Perseus receives a sword from the gods that slices through a block of marble without leaving a scratch on the blade. This is the weapon that he later uses to slay Calibos.
 * At one point in The Forbidden Kingdom, the blade of the Jade Warlord's weapon is smashed into the floor, and then dragged across the room. It cuts through the stone floor like butter. Granted, this is probably a magical blade, but still.
 * Machetes in Walk Hard. They have to be sharp to cut a person in half and impressively sharp to do so on accident, but it's reaching into the realm of the absurdly sharp when you can cut yourself in half by accident.
 * A scene in The Bodyguard involves a katana and a silk scarf. The scarf falls across the katana's blade and is sliced in half by its own weight.
 * Hilariously inverted in Hot Shots: Part Deux; Topper swings a sword through a candle, and it passes clean through... only for the sword to break a moment later.
 * Ninja Assassin has this on every blade we ever get to see. The swords can cut a man in half, and on one occasion, the protagonist is seen slicing open a wooden floor with his kusarigama. The shuriken are also pretty sharp, able to slice a mans head in half or cut off two arms at once, without changing trajectory. The movie actually spends a lot of scenes showing ninjas sharpening their blades.
 * In Kick Ass, Hit-Girl (a 10-year-old girl) uses a double-bladed weapon to cleanly and casually slice the leg off one opponent, then stabs her blades through a metal door.
 * Dragonslayer. Galen's lance, which is aided by a magic fire to make it sharper than sharp. It slices through the anvil with little effort.

Literature
""Every established kitchen has one ancient knife, its handle worn thin, its blade curved like a banana, and so inexplicably sharp that reaching into the drawer at night is like bobbing for apples in a piranha tank.""
 * Discworld has several examples of this:
 * Both the scythe and the sword of Death, especially in Hogfather. The edges of these weapons glow blue because of the air molecules being sliced in half all the time. The sharpness even extends a few inches beyond the blade due to the impossible aura of sharpness. In Reaper Man, Death sharpens his scythe on sunlight, and then tests it by cutting a sentence Miss Flitworth is speaking into its individual words.
 * Death defeats his evil replacement with an ordinary field scythe sharpened by his own pure rage. Rage isn't even "real," like light, it's just an abstract concept.
 * Carrot's sword is sharp enough to pierce a solid stone pillar. It is the long-lost sword of the Kings of Ankh, and the Disc's rules of Narrative Causality insist that such a historic weapon must be sharp enough to do such things. His ancestors specifically didn't want a magical sword; they wanted a sword that was really good at killing people.
 * The sword Roland uses to kill the bogles in Wintersmith is literally made out of sharpness.
 * In Interesting Times, when a small army of samurai demonstrate their absurdly sharp blades by throwing silk cloths in the air and slicing them in two, a reference to the old Saladin/Richard legend. Combat Pragmatist Cohen the Barbarian claims he can do the same with his ancient notched sword -- then, while they're all looking up at the handkerchief, he and his men decapitate nine of them. In The Last Hero, however, Cohen uses the same sword to roll a seven with a six-sided die by slicing the die in half while it's in the air, so his sword must be quite sharp.
 * Subverted in Wyrd Sisters, in which Granny Weatherwax performs this trope's typical demonstration (slicing cleanly through a solid object) with a blunt copper stick, which she's using as a substitute for a real magic sword in a demon-calling ritual.
 * Tiffany does the same trick Weatherwax did with a frying pan in The Wee Free Men.
 * Witches Abroad has a much more mundane example. Definitely Truth in Television:

""They are wood, but they are anything but ordinary. There are no other such weapons anywhere in the world. They are blackwood plus history, blackwood plus a little of every weapon that has ever been. There are the spears of the great Zulu impis in each edge, the power of Tamerlane's hordes, the thrust of Caesar's legions. On the very edge of each swim things that race the components of existence around racetracks on which the beginning and end of the universe is the bet. They contain weapons that have not been and weapons that will never be. They are blackwood plus all that plus Nafasi. Into them he has put his heart and soul and much more. They will cut well. I think they will even cut a shetani.""
 * The variable sword used in the Known Space stories of Larry Niven is a length of monomolecular wire held straight by a projected stasis field. There's a little red ball at the end of the wire so the wielder can tell where the otherwise invisible "blade" ends.
 * Larry Niven's short story "Not Long Before the End" (a part of his The Magic Goes Away universe) features Glirendree, "the most powerful sword in the world". It can cut through anything and makes its wielder immune to all magic. On the other hand, it is also a parasitic demon forced into the shape of a sword that leeches its user's life away, giving him no more than about a year of glorious victory before killing him of old age.
 * One of the evil empire's primary advantages in the Farsala Trilogy is that their folded steel blades ('watersteel') can cut through the Farsalan weapons, though with their superior numbers, much smaller egos, and much greater brains than the first line of Farsalan defenders they hardly need them.
 * The subtle knife from His Dark Materials. One side is so sharp it can slice though any matter effortlessly, including Sky Iron. The other side is so sharp it can slice through the boundaries separating other dimensions. Both edges are so thin and sharp that the end of it can't be seen with the naked eye. It also comes with a special scabbard, which really just holds the grip well.
 * And it gets points for being the only weapon capable of killing an omnipotent god who may or may not exist, and so also satisfying the actual philosophical definition of absurdity.
 * Basiclly, this is a knife that can cut and/or kill ANYTHING.
 * Some incarnations of King Arthur's sword Excalibur fit this trope. Depending on which legend you're reading (and which interpretation of the legend), Excalibur is either the most powerful blade ever worn by a British king, or else was just a sword. Many linguists believe that "Caliburn" (which became Excalibur) is an Anglified spelling of a Welsh phrase meaning Cutsteel.
 * In the Cross Time Engineer novels, Conrad Stargard has a sword that regularly slices through armor, body parts, anvils, and other swords. He thinks it is just really good steel. In reality, it has a diamond edge and was made by the same highly advanced people who accidentally sent him to the 13th century.
 * In the Sten novels by Allan Cole and Chris Bunch, the signature weapon of the eponymous hero is an absurdly sharp knife that can cut almost everything, even diamonds. And he keeps it hidden in his arm.
 * In Lin Carter's Dragonrogue, the hero, Kesrick, has a sword that, because of the magical gem in the pommel, can cut anything -- even adamantium.
 * In his World's End series, Carter again uses a Super Sharp Sword, in Ganelon Silvermane's "Silver Sword", although it won't quite cut anything -- there are limits, it seems.
 * In The Silmarillion, the knife Angrist, a knife that can "cleave iron like green wood..."
 * In Lord of the Rings elves can make sharper blades than anyone else and the blades keep their edge forever. Then there's Narsil. An absurdly sharp blade in elevn terms.
 * Narsil wasn't forged by the Elves in its original state but by the Dwarves, (Telchar of Nogrod) and survived for thousands of years before being broken (and certainly even an Elven blade would not likely have survived being stomped by Sauron). It was only after being reforged as Andúril that the Elves had any hand in it. In fact, when it comes to the quality of the metalwork itself, weapons of Dwarf-make generally seem to be given the edge by Tolkien (in keeping with the Germanic inspiration throughout the Legendarium).
 * A Song of Ice and Fire,
 * Valyrian Steel blades are far sharper and stronger than the best castle-forged steel. Forging the metal is a magical process that has become Lost Technology after the fall of Valyria. It has a smoky, rippled appearance that resembles Damascus Steel.
 * Dawn, the ancestral blade of House Dayne. The blade was forged from meteoric iron and is hinted to be of extraordinary quality. Arthur Dayne, the Sword in the Morning, notably used it to hack a foe's sword to bits, then chivalrously allowing him to retrieve another sword before slaying him. Jaime Lannister also recalls that the sword cut through his tunic and into the flesh beneath when Dayne tapped it against his shoulder to knight him.
 * The eponymous Sword of Truth can cut through anything that its wielder perceives as an enemy -- and unless you can find the strength to kill something you love will not touch an ally. Here, at least, it's explicitly magical. Needless to say, it's dangerous in the wrong hands.
 * Averted in the TV series, because the producers decided the clash of steel on steel was cooler.
 * In The Tale of Five novels by Diane Duane, when Segnbora is literally at death's door, she acquires a sword made by her ancestor from a fragment of that door, named Skadhwe. Skadhwe can literally cut through anything and lacks both a hilt and a flat (and is implied to have a will of its own), which would be a problem in wielding. So Duane adds the exceptions of "not its current owner", and "not anything its owner doesn't want it to cut", making Skadhwe probably the most convenient and least scary example of this trope.
 * Kosall in The Acts of Caine combines this with Vibroweapon.
 * In the Forgotten Realms there is the sentient sword Khazid'dhea, a blade that wants nothing more than to be wielded by the greatest swordsman there is (and to prove this by having said swordsman kill every other swordsman in the world). It is telepathic and can reshape its hilt to its owner's desires and incidentally inspire its wielder into a berserker frenzy if it gets bloodthirsty enough. It can also take chunks out of stone and never needs sharpening. Its name means, in the Drow tongue, "Cutter".
 * In Everworld, Coo-Hatch steel is used to make Absurdly Sharp Blades. The Coo-Hatch show off by cutting a tree into pieces, which stand for several seconds before falling, and then cutting the falling pieces with throwing blades. Later, a Coo-Hatch pocketknife is used to tunnel through rock. Very slowly.
 * Matt Mantrell in Christopher Stasheff's Her Majesty's Wizard conjures himself a sword made of pure black diamond with a specified "monofilament edge". He uses it to cleave significant distances into, if not actually through, armored knights.
 * In The Inheritance Cycle, Angela the Herbalist has a sword she calls "Tinkledeath" which is so sharp that it can literally cut through anything as if it were custard. Throughout the series, all Riders' swords are imbued magically such that they never rust or dull and can defeat or outright ignore most enchantments. They're also forged using a rare meteorite that the sword smith Rheunon named "Brightsteel" which has a notable crystalline structure. The same is true of Eragon's first Riders' sword, Zar'roc. After getting a new sword in Brisingr, Eragon was able to cut through a portcullis and then the door behind it.
 * Also averted once in Brisingr. Eragon goes looking for a replacement sword (long story), and a Varden smith gives him a falchion made of normal steel. He says he'll true up the edge with magic, and the smith tells him it's a bad idea because the blade will chip.
 * The contemporary fantasy novel Into the Out Of by Alan Dean Foster features an African master woodcarver who furnishes the heroes with wooden knives and spears so sharp they give you a paper-cut like cut just from touching the edges of the blades and can be thrown right through a wall. You can't even quite make out where the edge of one of them ends and the air begins, they're so sharp. As one of the characters describes them:


 * In one of the Left Behind novels, Carpathia is slain with a sword that's supposedly sharp enough to sever half of someone's fingers off, before they even notice they're being cut.
 * The Wheel of Time series brings us Power-wrought blades. They can cleave through metal armor and the tough flesh of a Trolloc with limited resistance. Lan notes that they never need to be sharpened though some men have been known to try, resulting in wearing a whetstone to nothing for no good reason.
 * "One, two! One, two! And through and through, the vorpal blade went snicker-snack!" - from Jabberwocky, in Lewis Carroll's Through the Looking-Glass and What Alice Found There (1872).
 * The Posleen in John Ringo's Posleen War Series have monomolecular blades that can carve up an Armored Combat Suit as easy as a Ginzu knife cuts through a tin can. And then they can slice a tomato so thin you can read a newspaper through it!
 * Brasyl, by Ian McDonald, one-ups monomolecular-edged knives with the Q-knife -- an edge that can cut quantum strings. Y'know, the stuff that decides matter is matter. If they ever break, the fragments sink towards the Earth's core.
 * In Snow Crash, by Neal Stephenson, Dmitri "Raven" Ravinoff uses knives made of knapped glass with monomolecular edges. They slash through Kevlar body armor, thick bamboo and people quite effortlessly, though
 * The main character, as well as just about everyone, in Sergey Lukyanenko's A Lord From Planet Earth series wields a monoatomic sword (AKA a planar sword). The main character, in fact, dual-wields them and carries them on his back ("Just be sure not to cut off your own head when taking them out."). As expected, the sword can cut through any known material. Despite the presence of various energy weapons, swords are still the preferred weapon due to the common use of neutralizing field generators that miraculously cancel out any destructive physical, chemical, or nuclear reaction (the field can even stop matter/antimatter reaction), leaving close-combat weapons the only possible method of killing. This also adds a measure of honor to battle, as combatants are on even footing. The difference between Medieval swordfights and combat with planar swords is that, during strike, one of the swords will invariably slice through the other. The trick is making sure you hit the opponent's sword at just the right angle with a thinner blade. The blade dulls with each strike and swing, requiring it to be periodically sharpened by a button on the hilt (a blade can only handle about 1500 sharpenings). Being a battle-hardened Earthling, the main character comes up with some nonstandard (and questionable) applications for the technology. He creates a throwing disc with monoatomic edges, which can literally take a person's head off. Later, he uses smaller hollow-point monoatomic discs that fire from a blowgun. He also develops (by accident) a way to use the sword to kill someone wearing a specially-designed armor that mostly protects the wearer from the sword (by holding the thin wounds in place until the body heals them).
 * Flann O'Brien's The Third Policeman features a spear so sharp that if you were to prick yourself with it, your finger would begin to bleed about two inches before the point appeared to reach your finger. In fact, when your finger starts to bleed, the spear point had penetrated your skin 2 inches ago, but was so thin it slipped between the atoms of your finger without causing any damage.
 * In the Star Trek Novel Verse, the Tholians have these. The edge of the blade is a single molecule thick. The swords become important to the plot in the novels The Sundered and Reap the Whirlwind
 * Klingons get them in places as well, in the form of Blood Swords, so named because they absorb blood and grow darker with use. When the sword turns completely black, it's full and you start another one, but you keep wearing the previous one to show WHY you have such a pale Blood Sword. They don't look all that special otherwise...until you find out that they can take pieces out of the nigh-indestructible metals used in starship hulls.
 * In Man of the Ice Garden Vuko Drakkainen, visitor from future Earth on a primitive planet, uses Nordland Aeronautics shinobi ken sword with "monomolecular blade". He once made a swing at a "monster" and accidentally cut through the ceiling without even noticing until some of its parts fell down. Also the dog, which hit the ground twice.
 * Animorphs has Andalite tail blades that seem to be able to cut through pretty much anything.
 * The main character of the Safehold series has one of these, it's made of some super-hi-tech alloy that's nearly indestructible to boot, he actually considered making an even sharper blade with an edge Sharpened to A Single Atom, but decided that was overkill. It helps that the character in question is a Ridiculously Human Robot with Super Strength who can thus put enough force behind the blade to slice an opponent's own sword into bits. Later he gives another character a similar blade.
 * There's one of these in "The Magic and the Healing" by Nick O'Donohoe.

Live-Action TV

 * Xena: Warrior Princess: Xena once described her power to kill gods as the "Ability to pierce the veil of immortality". Based on this, it can be fairly assumed that killing gods is accomplished by cutting through what makes them immortal.
 * Another god killing item, called the Dagger of Helios, was featured on Xena, and could be assumed to work the same way as the Hinds Blood.
 * In defense of the Hinds Blood's status as being abnormally sharp, Hercules managed to stab it into the stone rail of Ares temple with little effort. Understanding that this is the super strong Hercules, other knives could have been crushed, or not gone into the stone, however the Hinds Blood Dagger cut right into the rail, and remained there until Xena had it moved.
 * In an episode of Mister Rogers Neighborhood, Jay O'Callahan told the story "The Bubble", about a king stuck in a giant bubble and his attempts to get out. One of the knights who failed to pierce the bubble had a sword so sharp it "cut the wind and made it bleed".
 * Parodied in an episode of News Radio Matthew gives Bill a katana which Bill thinks is fake. When Bill realises it's real he drops it and it cleanly cuts off a piece of a nearby table as it falls.
 * The 1998 television series Merlin has an example of Excalibur that fits this interpretation. Just parrying a weaker sword will cut the weaker sword in half.
 * An episode of Warehouse 13 revolved around the threat of the assembly of THE Masamune. The sword was so sharp, it could cut through light, rendering the user invisible. That was clearly a bit of hyperbole though, since that function didn't work until the tsuba (the little circle thing above the hilt) was reattached. That said, the sword is absurdly sharp in its own right, as it was able to slice through a computer monitor effortlessly.
 * Inverted in sentai shows: Swords don't cut, but rather cause small explosions where they connect.
 * In an episode of Castle ("Heroes & Villains", s4e2), a victim is laterally bisected apparently through his skull by what turns out to be a samurai sword.
 * Pretty much every Highlander episode with a beheading...most swords, with the possible exception of a katana, can't sever a human head in one stroke.
 * In Kamen Rider Fourze, this is more of an absurdly sharp claw, given that the wielder is the Cancer Zodiarts.
 * One of the Salamanca cousins in Breaking Bad carries a chromed fire axe. It's sharp enough to stick in pavement just from being accidentally dropped.

Myth & Legend

 * In Norse Mythology, the Dwarf-forged magic sword Tyrfing could cut through metal and stone as if they were cloth. Needless to say, it could wreak havoc on an opponent's armor and weapons (to say nothing of the opponent themselves). Especially since it was never supposed to miss.
 * In Irish myth, Cuchulainn's sword can shave a hair from the skin without cutting the skin, or cleft a hair floating on water in twain, or cut a man in two "that the one half of him might not miss the other for some time after".
 * There are claims that certain units of lancers from Eastern Europe and Eurasia (it has been attributed to Polish lancers and Cossacks) would shave with the tips of their lances before battle, and if their commander could see any stubble or nicks on their chin, then their weapons weren't sharp enough for battle.
 * A popular Japanese legend tells of a competition between two famous swordsmiths: brilliant but slightly unbalanced Muramasa Sengo, and even more brilliant and universally revered Masamune. Each smith held his sword tip-first into a gentle brook, with the edge facing upstream. As leaves floated down on the current, Muramasa's sword cut them neatly in half as they wafted against the blade. Leaves that encountered Masamune's sword, however, would make a 90-degree turn and avoid the blade altogether, in a Crowning Moment of Zen. In other versions of the legend, the leaves that Muramasa's blade cut, Masamune's blade healed together. In yet other versions the blades were placed in the river and floated downstream. Muramasa then argued that his blade was finer since it cut the leaves, Masamune pointing out that such a blade was inherently evil and bloodthirsty, which his wasn't, therefore was superior.
 * In American tall tales, Pecos Bill's razor was so sharp he shaved with just the shadow of it! (Which means he didn't shave so well on cloudy days, when the shadow was dimmer and fuzzier.)
 * The Germanic tale of Wayland/Velent/Völund/whatever has the hero make a sword, Mimung, so sharp that he slices the competing smith Amilias from the head down in half with one stroke, complete with his extremely thick armor, and Amilias didn't discover this until he was asked to shake, at which point he fell apart.
 * There's an apocryphal legend about Richard the Lionhearted having a conversation with Saladin about their respective swords. Richard requests an iron bar, and chops through it cleanly. Saladin shrugs, and requests a silk pillow. Richard's sword fails to even mar it, while Saladin's scimitar slices it neatly in half. More fanciful versions of the story have Saladin letting a silk veil fall across the edge of his scimitar, and cutting itself in half, while Richard was able to split an anvil.
 * A 20th-century apocrpyhal tale has a burly Afrika Korps infantryman going hand-to-hand with a Gurkha. The latter delivers a throat-high slash with his kukri, which the German doesn't even feel. "You missed!" he snarls, preparing to skewer the little Nepalese guy with his bayonet. Unperturbed, the Gurkha just says "Nod your head...". And, of course...
 * Islamic folklore has Zulfiqar, Ali's sword. it was found by Muhammad in the meccan temple of Ishtar, and described as a long scimitar with a curious forked end. according to the legend, the archangel Gabriel constantly chained the true power of Zulfiqar since it was so sharp that at full force it could create Kamaitachi that would cut mountains apart. another myth says that Ali killed an enemy knight by beheading the horse and slicing the knight in half with a single slash.
 * According to the Norse/Germanic saga of Sigurd/Siegfried, same hero's sword Gram/Balmung/Nothung was so sharp that he tested it by slicing an anvil in half.

Tabletop Games

 * Most combat blades in Warhammer 40000 are Sharpened to A Single Atom as a matter of course. Combat knives, swords, some weapon ammunition, etc. It is quite commonplace in their armies. There's also fractal blades, or C'tan Phase Swords, which can slice through anything, due to the fact that they're made of Necrodermis, which is what C'tan are made of. Trying to attack one of them with one will cause it to merge with their body.
 * Warhammer Fantasy has the Runefangs, dwarven-made swords that are wickedly sharp. There are twelve of them, each made for one of the Elector-Counts of the Empire. None of the people the swords were made for lived long enough to use them, because the dwarves wanted them to be perfect and it took longer than a human lifetime for the smith to make them all. The descendants of the original intended owners use them just fine.
 * A wizard using the Lore of Metal can cast Enchanted Blades of Aiban to give an entire unit of combat troops Absurdly Sharp Blades.
 * Warhammer Fantasy Roleplay allows runesmiths to create more Runefangs by adding the master rune of Alaric the Mad (the smith of the original Runefangs) to weapons. Lest you think this a Game Breaker, creating a new Runefang can only be done by a master runesmith (a tertiary career), will take years for a Player Character even without failing any checks (making a sword that can become an Absurdly Sharp Blade for a single blow is easier, taking a few days' off-time), and it's explicitly verboten for a runesmith to ever create two weapons with identical runes on them (that Alaric did this is why he's called 'the Mad'), and master runes occupy all slots on a weapon.
 * Dungeons & Dragons
 * Vorpal weapons from automatically decapitate the target on a natural 20, no matter the critical threat range. Likewise, a Sword of Sharpness can dismember a target on a natural 20. Lastly, the keen property, or the keen edge spell, makes a critical hit more likely.
 * In the fantasy genre, vorpal blades are not merely absurdly sharp; they represent the absolute limit of sharpness. Vorpalization is a process in which a blade or other edged object is magically imbued with an edge that converges to zero thickness, making a vorpal sword the sharpest that a weapon can, in fantasy, hypothetically be, and sharper than anything in reality can actually be.
 * Weapons made of adamantine bypass an object's hardness. That means that a slice from an adamantine blade will damage an iron door just the same as it would a wooden door or even a piece of cloth (of course, the iron door would still have more hit points, but the point is that even the tiniest strike will do some damage to the door). Oddly enough, this even applies to bludgeoning weapons, so that with about two dozen average whacks from an adamantine light hammer by a character of average strength one could bust through an iron door.
 * The major artifact sword Angelwing Razor is so sharp, it can cut through literally anything, bypassing all forms of hardness and damage reduction. this includes barriers of pure magic that have no actual material substance.
 * The Everway RPG had among its legendary artifacts a sword named the "The Edge of Light and Darkness", which was created to exemplify 'the dividing line between Is and Is Not.' The Edge of Light and Darkness could cut anything its owner could conceive of cutting, and could wield the blade with sufficient skill to hit. In addition to the relatively mundane task of doing a Clean Cut through any physical substance, known examples include cutting through the fabric of space-time to create portals between alternate universes, killing an opponent by cutting his soul free of his body (without actually leaving any physical wounds on his body), and destroying a pocket universe by slicing the substance of reality into its fundamental elemental components.
 * 7th Sea has the crescent-shaped scythe of the NPC Captain Reis, which allows him to cut through anything -- even armor made from Dracheneisen, the 7th Sea version of Mithril, gets cut in half like so much butter.
 * New World of Darkness got a supplement on 1st April called Dudes of Legend: How To Be Fucking Awesome. It contained (among rules for using your genitalia as a bludeoning weapon, instituting experience charts for kills and other things that ran completely contrary to the intended feeling of nWoD) a hack that let you wield a katana that had the 7-Again quality, allowing you to reroll any result of 7 or higher on a d10. Considering that the system only counts sucesses at 8 or higher, and rerolls at 10, you will reroll every sucess you manage to get, again and again. It's explicitly intended to simulate these kinds of weapons.
 * Fading Suns has wireblades -- monomolecular swords that will cut through anything with ease. In game mechanics, this means they ignore any armor the opponent is wearing.
 * Shadowrun had monomolecular axes that possessed a monofilament edge capable of cutting through virtually anything. It tended to lose its edge quickly though. In later editions other bladed weapons could be outfitted with a monofilament edge, and then there's the monofilament whip, noted by the 'in character' reviews of the characters in the game setting to be as big a threat to the user as to a potential enemy.
 * Tabetop GameGURPS Ultratech has a number of (increasingly super-science) ways of justifying this. Superfine blades divide damage resistance by two. Monowire blades divide damage resistance by ten. Nanothorn blades divide damage resistance by ten and shreds the bonds that hold the atoms in molecules together.

Theatre

 * Based on stories similar to those in the Myths and Legends section, above, Richard Wagner in his music-drama Siegfried, has the eponymous hero, after he has reforged his father's sword Nothung, use it to slice in two the anvil he has formed it on.

Video Games

 * Devil May Cry displays this trope every time a sword is used in a cut scene. Word of God says that Dante's blade is capable of slicing absolutely anything in the physical plane. Not very convincing after the series' later graphical pushes (the rust and nicks become more pronounced).
 * The Rebellion is upstaged by that of the Yamato, Vergil's trademark sword, which is capable of cutting through dimensions.
 * Bishamon's ancient blade, Kien. The sword was originally forged because talented warriors were frustrated that their swords had dulled irreparably. Thus Kien was crafted - using forbidden techniques - in such a way that it actually became sharper the more it was used, meaning a stronger blade from multiple battles. However, Kien eventually fell into the presence of the demonic Hannya - "the armour of hate" - and was subsequently corrupted, gaining a thirst for blood...
 * Dwarf Fortress has body parts being severed off and sent flying away and skulls getting crushed through the brain as a general part of its fighting mechanic. The kicker? Every weapon or physical strike interacts with body parts in the same way, so the handy Copper Dagger that all adventurers start with can literally slash Badger-Boars and Boogeymen in half in one turn. As can whips, scrooges, flails, maces, hammers, pikes, shields, fists, teeth, ...
 * Adamantine is so sharp a battleaxe of it will cut through a stone floor under its own weight. Keep in mind it has approximately the density of styrofoam.
 * Throughout the Final Fantasy series:
 * In Final Fantasy VII Sephiroth's Masamune: in one scene in Crisis Core where he's fighting Angeal and Genesis, Sephiroth tears apart a gigantic cannon with it by slicing through the barrel with Sword Lines from the blade during the fight. That's one bad-ass sword.
 * Odin's One Hit Kill attack cuts (Zantetsuken) all monsters on the battlefield in half.
 * In Final Fantasy VIII, Seifer cuts Odin in half.
 * Which caused the Zantetsuken to go spinning off into the sky, cutting a hole clean into another dimension. Specifically, the Interdimensional Rift from Final Fantasy V, where it was caught by Gilgamesh.
 * In Final Fantasy VII: Advent Children/Complete, Sephiroth's Masamune and Cloud's First Tsurugi blades are capable of not only slashing cleanly through massive pieces of concrete building that are far larger than the swords themselves (which is saying something), but setting the edges of the cut concrete ON FIRE. Of course, the swords, despite repeated clashing, never damage each other.
 * In Half-Life 2, the circular sawblades first seen in Ravenholm will stick into most anything when fired using the Gravity Gun, be it dirt, wood, or reinforced concrete. They can also be easily pulled out again, completely undamaged, without even leaving a scratch on whatever they were planted in.
 * The Keyblade in Kingdom Hearts. Even the Kingdom Key, which has a blunt edge, can cut through buildings in Kingdom Hearts 2.The explanation is that the actual blade is the magic around it, thus, no matter how blunt it may look, the weapon cuts like a well-crafted sword. Some keyblades, though, have explicitly sharp heads, and are basically fancy axes (and the original Infinity Plus One Sword, Ultima Weapon, was s sword with a strange guard around the blade).
 * Samurai Shodown II features Cham Cham, resident Catgirl with her Improbable Weapon, a wooden boomerang used for melee combat. It's considered sharp by the game, enough that (in the original releases) you could trigger the game's Diagonal Cut death animations if you ended a match with a strike from it. Or if you pitched it at an enemy. Her claws work the same, too. 'Oh! How dangerous a boomerang is!'
 * In Super Robot Wars, there is nothing that Sanger Zonvolt's Zankantou/Colossal Blade cannot cut. It achieves this by having thrusters on the non-bladed side, allowing it to keep cutting even when it should get lodged into its target. This allows it to cut through huge battleships, hence the name "Zankantou", but it still breaks when it tries to cut into Giganscudo's Unobtainium armor. The Type 3 blade, however, is made of liquid metal and Runs on Badassoleum, making it more an example of this trope.
 * Youmu's sword from Touhou. "The things that can't be cut by my Roukan Blade, forged by Youkai, are close to none!" It is able to cut spirits and possibly other intangible things. However, her other sword, Hakurouken, while not as absurdly sharp it has the power to cut confusion, to the point of potentially giving instant enlightment to spirits. It however still hurts humans.
 * In Touhou Soccer, she takes this to an over the top level by cutting the moon in half. As the description for Roukanken the equippable item in Touhou Soccer states: "A certain gardener's personal sword. It cannot cut through the ball. Just what is that ball made of, I wonder."
 * At the beginning of Xenosaga Episode II, Jin is introduced when he slices a Humongous Mecha in half with his sword while on foot.
 * The retractable blades on the Scorpions in Unreal Tournament 2004 are mentioned to have an edge that is exactly one atom thick. However, while they will instantly cut any on-foot opponent they touch in half, they break off if they touch anything else.
 * Anna's BFS from Mana Khemia Alchemists of Al Revis can somehow cut open reality, allowing her to enter other dimensions for her special attacks.
 * In Nethack, the Tsurugi of Muramasa and Vorpal Blade each have a 5% chance of bisecting (in the case of the former) or decapitating (in the case of the latter) what they hit, causing instant death.
 * In Chrono Trigger, once repaired the Masamune sunders a passageway into a moutain.
 * In Skies of Arcadia, Ramirez' sword is described as being sharp enough to cut through light (which appears to be evidenced by his powerful "Silver Eclipse" attack).
 * In Starcraft, the Zerg Ultralisk's Kaiser Blades are said to have a "monomolecular edge".
 * The trailer for Metal Gear Solid Rising pretty much consisted of four minutes of Raiden using his high frequency blade to turn people into deli meat, slice vehicles and buildings in half, and cut up watermelon for kids. His sword in Metal Gear Solid 4 is similar.
 * The swords in the MGS series are technically subversions as its not the sword itself thats slicing apart the environment, but rather the heat generated from the high-frequency friction of the blade.
 * Rayne's wrist blades in Blood Rayne cut through bone as easily as air. Also wood, stone, many kinds of metal -- anything that can be demolished in the environment she can put a blade through as easily as waving her hands.
 * Fallout New Vegas - Dead Money: The Sierra Madre Casino's kitchen staff believed that the Cosmic knives they were supplied were too sharp for their needs. Sure, they could slice through a T-bone steak with no problem, but they'd cut through their cutting boards and their own fingers just as easily.
 * In Deus Ex, JC has to end a war between two gangs over the production of a self-sharpening nanotech sword. While the impetus for the war stems from its use as a proof of technological superiority, it's also very effective.
 * Alex Mercer in Prototype can form these out of his own arms, be it claws, a whip or just a giant blade.
 * Geralt of Rivia's swords in The Witcher are described as being absurdly sharp. Later on in the game if the player

Web Animation

 * Baninja's "katanana" in Banana Nana Ninja is a tiny sword wielded by a banana, which can cut through the roof of a bus and cleave through Humongous Mecha. He stores it in his head, disguised as his stem.
 * In Red vs. Blue Revelation, Tex's combat knife is sharp enough

Webcomics

 * In Garth Graham's Finder's Keepers, there is a knife that is literally, the Cutting Edge. Of course, Finder's Keepers is about the realm of Faerie, so things are automatically literal.
 * Almost every blade wielder in The Order of the Stick can chop through a body with one casual swing, but halfling Belkar's tiny daggers seem particularly able to cleave a human skull in half with a flick of the wrist. Of course, this may be a visual representation of the unrealistic hit point system in action. This is particularly unusual when you consider that Belkar supposedly dulls his knives instead of sharpening them (he wants them to hurt more going in).
 * "How did I cut tha tentacle wit a hammer...?"
 * Bro's swords in Homestuck have cut through wooden ventriloquist's dummies, (extremely shitty) swords, meteors and the design on Dave's shirt without cutting the shirt in one stroke. Later he tops the record once more, by cutting into the Beat Mesa, which otherwise requires Infinity Plus One Magical Needles to do.
 * In Gunnerkrigg Court, the . "The keenest blade you will ever find! Be careful with it, because it could cut the very earth!" . Annie and Kat "did some test on it and found it to be really damn sharp". That is, they dropped a steel bearing on the edge and it continued the fall in two pieces.
 * It's actually sharp enough to ''. And it laughs while doing it.
 * In The Dreadful, during a non-canon advertising intermission, heroine Kit is depicted effortlessly slashing villainous monkeys to bits with a sword that is apparently made from a single large feather.
 * In Sinfest, a comparision of swords includes one that cuts diamonds, and one that can cut paper dolls in mid-air.

Web Original

 * Black Knight in Marvels RPG wields Excalibur, which is so insanely sharp that he can cut through anything... and then comes all of its magic abilities.
 * Chapel manages to  with a sword she bought...at Ren Faire.
 * From the Global Guardians PBEM Universe: A Espada ("The Sword") is a Brazilian who can create a "sword" out of pure mental force that can cut through anything as long as he has confidence that it will. Pendragon, a British hero, wields the legendary sword Excalibur, and has yet to meet a substance it cannot hack through. Fey, a mystic swords man who claims to be from the elf-lands of Faerie, once used his sword to cut through a bank vault door, though he says it's all in the magic and not in the blade.
 * The sword Kamimura uses to sever Oran's chip-implanted hand and therefore save him in the Grand Finale of Broken Saints.
 * The Whateley Universe stories have a few of these. The magical sword Destiny's Wave, wielded by The Handmaid Of The Tao (a superheroine codenamed Bladedancer). In the hands of the rightful user, it can cut through anything (even unstoppable superhuman bricks), if the Tao requires it. At other times, it is as blunt and harmless as you'd expect of a blade made of white jade. And then there's Toni's mithril Kukri, Fey's scimitar Malachim's Feather, and Hank's PK shortswords.
 * Dominic's sword in Ather City. Don't bother asking which one, because it seems to spontaneously apply to every sword he picks up.
 * SCP-585 is a pencil sharpener which infinitely sharpens the points of graphite pencils. To the point of their being able to penetrate steel. And bedrock. And split atoms.

Western Animation

 * Samurai Jack's ancestral sword fits this bill very well. It can potentially cut through almost anything, but he has came across things that he simply wasn't strong enough to cut. It was a plot point at one time.
 * There was also a rather entertaining episode in which he proved that the sword wasn't everything- he took on an entire army of Mecha Mooks with a bamboo stick. And cut them in half with it.
 * The Scotsman's magical Claymore, being just as powerful as Jack's katana and capable of wounding Aku, averts the idea that Katanas Are Just Better.
 * Saluk from Aladdin and the King of Thieves has brass knuckles with blades. He can use them to slice his way down a cliff-- and they don't get dull at all.
 * Avatar: The Last Airbender has Sokka's "space sword". Its sharpness doesn't come up that often, but during the invasion, he cuts through a ballista in one swing. In the finale,
 * Much earlier in the series, in "The Blue Spirit," the titular masked spirit uses dual Dao sabres to cut right through the chains holding Aang captive. In a single stroke.
 * Kung Fu Panda featured the Sword of Heroes. "Said to be so sharp you can get cut just by looking at-- Ow!"
 * In one episode of G.I. Joe, Cobra swordsman Storm Shadow gets his hands on the original Excalibur, which among other things can cut right through an enormous stone pillar with one swipe.
 * Near the climax of The Hunchback of Notre Dame,, all the while cleanly slicing through stone gargoyles attempting to slash at them.
 * Related to this trope is the old cartoon gag of a blade being sharp enough to split a hair neatly in two. A notable example is in the Looney Tunes short "Ali Baba Bunny", where Hassan's scimitar comes short of piercing Daffy's skull but it does part a single hair (feather?) on the top of his head.
 * In one episode of the Cartoon Network show Adventure Time, Jake and Finn's tree house begins to move. Then it cuts to the bedroom, showing Finn's sword toppling over and completely slicing through his bed.
 * In Batman Beyond, Assassin Curare uses a monomolecular sword that effortlessly cuts through anything standing in the way of her swings. Of course, the ultra-Gorn-fest that would ensue if she used this on humans can't be tolerated in a kids' show so it was only used to slice into places.
 * Played With in the ThunderCats (2011) episode "The Duelist and the Drifter" where several swordsmen in an Adventure Town Invoked Trope this in the local sword competition, each bragging of their blade and striking a towering, giant boulder to see how deeply it cuts (one prideful Pig Man sees his sword shatter on impact.) Only young hero Lion-O makes good on his boast, as his Sword of Omens totally cleaves the boulder in two with a classic Diagonal Cut, winning him a hefty purse.

Real Life

 * To prepare a slide for an electron microscope, a diamond blade is used to get a less-than-paper-thin slice. Once properly sharpened, it's about a hundred atoms wide or so, and it will slide through your hand as easily as through the air.
 * There is another type of blade used in microtomes to prepare samples for the electron microscope: Freshly broken glass. Glass isn't precisely a solid, so the edge dulls quickly just by existing, but a fresh one is among the sharpest cutting instruments known to human science.
 * Knapped obsidian blades are a small and measurable number of molecules in thickness. And while diamond is the harder material, obsidian can be made sharper. The greatest of care should be used in handling obsidian knives and arrow points etc because they can remain truly Absurdly Sharp even centuries after being made and will cut you badly with even the slightest touch. The drawback of course is that being basically an exotic form of glass, they wear out quickly in use.
 * Obsidian blades are still used in eye surgery when a clean cut is needed.
 * Anthropologists and paleontologists have "tested" the technology available to Stone Age humans by using hand-knapped obsidian blades to butcher an elephant's carcass.
 * There are even legends from ancient cultures of swords with obsidian blades that could behead a horse with a single swing.
 * Single-layer graphene is probably the sharpest blade that can be made with conventional matter. It's a single atom thick, thinner than you can get pretty much any substance without distributed electron orbitals to stiffen it, and it's essentially the strongest material known that operates on that scale. Per unit area, it's stronger than diamond, though diamond is superior at greater thicknesses, due to graphene's weak inter-layer binding.
 * Traditionally, the balisong was tested before it was sold. The vendor would take out a few one-peso coins and stab right through them with the blade. The blade would be completely undamaged, and the coins (and table) would have holes in them.
 * The Aztecs used obsidian blades embedded in a wooden club to make a deadly weapon known as the Macuahuitl. The blades were easily sharp enough to decapitate a man, and can supposedly decapitate a horse if used correctly.