Put simply, this is an ally (usually) who can serve as a weapon. Not in the sense of an Attack Animal or a particularly useful One-Man Army, but in that their ally picks them up and uses them to strike down their foes.
Sometimes more exotic solutions present themselves of course, with characters who are capable of Voluntary Shapeshifting into a weapon (typically a powerful one, otherwise they would just be cutting their forces in half). Weapons which can manifest some sort of Avatar or otherwise interact like any other character also count. A related trope is the Empathic Weapon, which seems to have some vague form of intelligence or link with its wielder but not enough to count as a person (although particular powerful examples might overlap with this trope under special circumstances).
An improvised version of this (i.e. picking up an ally and using them to strike an enemy) could overlap with Grievous Harm with a Body or Fastball Special if a habit is made of it (examples of these go on the relevant pages). If they're used as ammunition see Catapult to Glory. A Sub-Trope of Living Weapon.
Anime and Manga
- In Soul Eater the ability to turn into a weapon is essentially an ability some people happen to have. While they can do damage on their own, they're more effective when someone else wields them (explicitly acting as an amplifier for their wielder's own Ki Attacks).
- The weapon-people are stated in several places to be the results of experiments conducted by Arachne, combining the Witch Species' shape-shifting with normal humans.
- The Eldel Raids of Elemental Gelade are (generally hot) girls and women who form a bond with a human to tansform into absolutely devestating weapons. The downside to this is that they then have to re-charge through some way or another, for example, excessive eating or sleeping.
- The zanpakuto in Bleach are this in reverse in some cases; they start off as empathetic weapons and eventually begin to manifest a corporeal form to attack alongside their wielder. Most of these are just a more powerful weapon, but there are some exception's (Renji's turns into a giant snake, for example...with a Wave Motion Gun in its mouth).
- Lilynette is effectively Starrk's zanpakuto, as both were originally part of the same Hollow but are now in separate bodies. Ukitake and Kyoraku are quite bemused by seeing pistol!Lilynette and Starrk arguing loudly. Perhaps their own zanpakuto aren't so chatty.
- In the Zanpakuto Tales Filler Arc (which was semi-canon, since it was based on an idea that the manga's creater never made use of), all of the zanpakuto manifested humanoid forms (although this slowly wore off as they ran out of energy, so they returned to normal when the arc ended). It's implied that they appear this way in their wielders' Mental World but only Ichigo's (and the Filler Villain of the arc) has ever been shown.
- A Crowning Moment of Funny version happens in One Piece, when Zoro and Usopp are chained together with indestructible Sea-Stone handcuffs. Usopp attaches himself to Zoro's arm and is given a name as a katana, something like this.
- Magical Girl Lyrical Nanoha StrikerS has Unison Devices, which are basically tiny mages that can fuse with other mages and give them more power. Reinforce, Reinforce Zwei, and Agito are examples.
- Koyomi Sakuragi from Shiki Tsukai.
- In Yu Yu Hakusho, the older Toguro brother can transform his body into a weapon for the younger to wield. He can apparently turn into any weapon, though IIRC he only appears visibly as a sword and a shield. In the English dub, he claims that he can ever turn into a machine gun, which begs the question if he fires demon energy or pieces of himself as bullets.
- In The Sacred Blacksmith, all demon swords which exist long enough will become capable of shapeshifting into a human form and vice versa at will.
- Rosario + Vampire: Kokoa's pet bat, Kou, can become an assortment of weapons for her to use.
- Shining Tears X Wind has (mainly) attractive women being used as sword sheathes. The character reaches into their chest and pulls out a unique sword.
- Doctor Slump: Arale and Gatchan are sometimes used as weapons.
- In Guilty Crown, someone who has a Void Genome in them can extract Voids from other people. These can be anything from long swords to refrigerators.
- In the very first season of The Slayers, Rezo confronts Zelgadis for the Orihalcon Statue. Zelgadis grabs Lina, and well...throws her, letting her scream all the way. Since Rezo is blind, this proves to be a good distraction even though she misses Rezo himself.
- In Dinozaurs, the aptly-named "Dino Weapons" can change into weapons that attach to their fellow Dino Knights.
- In Nurarihyon no Mago, Yura Keikain's shikigami Rentei transforms into an Arm Cannon in Yura's arm that shoots a powerful stream of water.
- Kole from Teen Titans can turn herself into a crystal, and then her buddy uses her as a weapon. He normally uses her as a club.
- In Redwall, one hedgehog fought by rolling into a ball and having an accomplice roll him at the enemy using a long stick.
Live Action TV
- The Imajin of Kamen Rider Den-O. While most Riders of the series use the Imajin for a form change via Demonic Possession, Zeronos Zero Form and New Den-O Strike Form have their Imajin change into actual weapons.
- The Arms Monsters of Kamen Rider Kiva work a bit like the Imajin in that they transform into weapons that in turn cause a form change. Depending on your definition of "weapon", the living Transformation Trinket Kivat and his relatives may also count.
- The Magic the Gathering card Artillerize involves basically turning a creature into a missile (in-game, this translates as sacrificing a creature to fuel a direct-damage spell).
- Another way to invoke this trope involves Bludgeon Brawl, which causes all non-creature artifacts to be treated as equipment. When combined with Liquimetal Coating, which turns a non-artifact permanent into an artifact, it's possible for a creature to literally pick up a Planeswalker and smash things with him/her.
- Yu-Gi-Oh! TCG has the Catapult Turtle that does the same as the Artillerize on Magic.
- Bionicle: Click, a Scarabax Beetle, can transform into a shield for Mata Nui to use.
- Disgaea 3 introduced a mechanic to the series called "Magi-change". This allowed any monster type unit to fuse with a humanoid unit by turning into a weapon for them to wield for a few turns.
- The PSP Remake of Disgaea 2 has had this mechanic added.
- Castlevania: Symphony of the Night has the Sword Familiar, who is a standard familiar...until it reaches level 50, when it can be used as a very powerful sword.
- The video game EOE Eve of Extinction features weapons made by converting a human's neural structure into an operating system, the most powerful one's being the protagonist's girlfriend and The Dragon, who also happens to be The Man Behind the Man. Although its not made clear if former's an actual example of this, if she can project some sort of hologram or if the cutscenes show her in humanoid form for convenience sake The Dragon certainly is.
- Sam sometimes uses Max as a weapon or anything needed in the moment. Taking to some extremes in the classic Hit the Road where Max is part of the inventory.
- In BlazBlue Rachel Alucard uses her Non Human Sidekicks Nego and Gii as weapons (and shields).
- In the online game Ghost X you gain a "nanobot", which is basically a creature that can turn into a weapon.
- In the video game series Mega Man Star Force, Wizards, AMians, and FMians can all be considered this.
- In Mega Man Zero some cyber elves can be made into one shot weapons.
- Earthworm Jim is an interesting case in that the main character uses himself for several purposes, including as a whip and a grappling rope.
- The Legend of Zelda Skyward Sword: Fi may or may not be the Goddess Sword itself. Played straighter with Ghirahim, who is forcibly reconverted into the Bigger Bad's sword for the Final Boss battle.
- Maple Story has a recurring character in the Aran questline, Maha, the spirit of Aran's polearm. He gets indignant about being left behind, becomes sentimental when Aran remembers him (complete with Sand in My Eyes) and is responsible for at least one of Aran's job advancements, landing him squarely in type 2 territory.
- The Final Fantasy series has a few examples;
- In Final Fantasy VI, Umaro sometimes throws other party members (or himself) at the enemy as an attack.
- Rinoa from Final Fantasy VIII summons her dog Angelo for special attacks. In one of them, she launches Angelo from her arm, in the same way she usually launches her chakram.
- In Final Fantasy XIII-2, Mog serves as one to Serah, being able to transform into a sword or bow for her to wield.
- In Whiplash, the player character consists of a weasel and a rabbit chained together. Spanx (the weasel) can use Redmond (the rabbit) as a weapon by swinging him on the chain to knock over guards and generally cause mayhem.
- The Player Character in the game Knuckleheads is two heads connected by a Variable-Length Chain. One head acts as the anchor, while the other swings around to move and/or bash enemies.
- In Sonic Heroes (where you play as a team of three characters), your other two team members serve as projectiles for whichever of them you are controlling at that moment. Speed type characters use them to follow up their homing attack; flying types throw them and Power types spike them to enemies like volleyballs.
- Skies of Arcadia: Legends: Cupil is Fina's companion/pet, usually worn around her wrist as a bracelet. In battle, he can transform into different weapons and objects and attack enemies for her.
- In Adventurers! Spybot is able to turn into a BFG, which Tesla wields with her usual enthusiasm (it's implied he has similar weapon modes, but we never see them).
- One story arc of The Adventures of Doctor McNinja involved banishing a demon. There was a family of demon hunters who could do so, however the last in their line was the product of some serious inbreeding. As a result he was unable to use his legs, so Judy the Gorilla wielded him while he weilded his sword.
- In Transformers G1 Megatron had a gun as his alt mode (which ironically meant he relied on Starscream to wield him).
- Though in the opening sequence of the first season, he displayed the ability to shoot all by himself in his gun mode.
- G1's Galvatron didn't need anyone to wield him in his gun mode for him to shoot, nor did Shockwave (though Shockwave was once forcibly wielded by Bruticus and made to shoot his own security sentinels when the Combaticons invaded Cybertron).
- The Targetmasters, and G1's Sixshot.
- A number of Mini-Cons also have weapon modes.
- In the second season finale of My Little Pony Friendship Is Magic the Mane Six are battling a horde of enemies. Twilight is shooting magical beam attacks, and Pinkie Pie picks her up and aims her at a group of assailants. She even rotates Twilight's tail as though she were using it to fire off rounds like a Gatling Good gun.
- In the The Penguins of Madagascar short "Christmas Caper", Skipper uses Rico to shoot at Mr.Chew like a machine gun after he's swallowed a bowl of mints.
- A few of episodes of The Super Mario Bros Super Show had Snifits being used as guns.
- or, rather, his worm body