Hidden Weapons

Any weapon hidden in a creative place on a person's body. Not the same as a Victoria's Secret Compartment or Trouser Space. If the weapon is stored around the belt area, the trope you're looking for is Pants-Positive Safety. See also Anatomy Arsenal for implanted variants.

If there are lots of them, Extended Disarming may ensue. See also Hyperspace Arsenal.

Anime and Manga

 * In Baccano!, Nice Holystone hides a small bomb in her empty eye socket beneath her eyepatch.
 * Mihawk of One Piece wears a small knife as a necklace.
 * Hidden Weapons specialist Mousse from Ranma ½ keeps an innumerable amount of weapons stored on his person, whether simply tucked away inside his robes (ignoring such little things as bulk, size, and weight of the objects, which neither hinder him nor give themselves away,) snapped into the soles of his shoes, or even a length of cutting wire carefully rolled into the frames of his glasses.
 * Before Mousse there was Ryoga. He wore a massive number of bandanna's each one with a razor wire allowing him to throw them like shuriken. His bamboo umbrella weighs several tons and has razor edges, and even his belt can be snapped straight and wielded like a sword. However Ryoga's arsenal was passed over after being overshadowed by Mousse, and he mostly became a straight fist fighter focusing on unusual strength and endurance.
 * In Trigun, Meryl Strife has a bunch of tiny one-shot guns strapped to the underside of her cape and so it looks like that she wasn't wielding anything when she walks around with her cape around her shoulders.

Comic Books

 * The Girl Genius paper-dolls for Gil feature, according to the tailor-bot, "a panoply of hidden weapons for vicious backstabbing". Phil and Kaja, of course, say they don't see any.
 * Kit Willer wears a scabbard containing a hidden knife on his back, right under his neck. It does save his life from an arrow.

Film

 * Buster Keaton, in Our Hospitality, demonstrates an early example of this. While visiting his beloved's family, he reveals a large number of pistols concealed on his person.
 * From the movie The Jewel Of The Nile: "Jesse had a knife hidden in his boot." One wonders exactly how Jesse got it out when his hands were bound and he was hanging over a pit, mind you...

Literature

 * In The Gardella Vampire Chronicles, Victoria's hairdresser hides her stakes within her hairdos, for easy access.
 * In Yulia Latynina's Inhuman, the Villain Protagonist hides a gun-like mechanism that fires a diamond bullet in his semi-prosthetic leg when going to assassinate an otherwise Crazy Prepared Evil Prince (this being a distant future where projectile weapons are considered obsolete).
 * In Allegiance, Mara Jade keeps a hold-out blaster in a tiny holster in her boot.
 * She keeps one up her left sleeve at almost all times.
 * The Assassins' Guild members in the Discworld are frequently described as having weapons concealed all over their bodies, to the extreme that, when someone menacing gets near, everyone starts revolving in their clothes.
 * There's a scene in Neal Stephenson's Cryptonomicon where one of the characters spends two pages removing various weapons from holsters all over his body so he can lie down comfortably. Justified in that he's a Marine in a combat zone, but pretty funny nonetheless.
 * One scene in Shogun has Blackthorne, prior to acting as a distraction in the plan to liberate Toranaga's ship, borrow a few knives and start stashing them under his belt, strapped to his arm and so on. The surrounding samurai seem vaguely appalled. Later he's visited by Friendly Enemy Rodriguez who he orders searched, turning up knives and pistols hidden in his boots, sleeves, pockets and even in the band on his hat.
 * Lazarus Long from Robert A. Heinlein's Time Enough for Love is known in-universe to be a master at this. Usually favoring full Scottish garb for the sheer area where one can hide all sorts of surprises, one scene in The Number of the Beast has him strip searched almost to the point of a cavity search and remarking in his own head that he still had one holdout.

Live Action TV
"John: How many of those do you have? Ronan: How many do you need?"
 * The Doctor Who episode "Bad Wolf", had Captain Jack Harkness pull a gun out while completely naked. His assailants asked him where he got it from, to which he replied "You really don't want to know" before shooting them both.
 * One episode of Stargate Atlantis has Ronan produce a dozen throwing knives after being strip searched.

New Media

 * Admiral Harper of Open Blue keeps a court sword in his walking stick. Said walking stick also happens to be made of some pretty hard stuff, and so fares well as a Simple Staff. Flottenadmiral Nimitz from v2 - v4 keeps a dagger in the sole of his boot.

Tabletop Games

 * GURPS: Ultratech has the Finger Laser. It's fitted beneath the first layer of skin at the end of the finger. And to really shock people you can install a Ripsnake, which comes out of your mouth, the game advises using it while kissing someone for maximum effect.
 * Cyberenhancements being available generally allow an enterprising individual to do full array of these tricks.
 * Forgotten Realms has an example of weapons disguised as other weapons: a wizard detective carrying a pair of sword scabbards. But there are daggers inside, and the leftover space is used to stash two wands per scabbard.
 * Warhammer 40,000 Roleplay series gear includes the Concealed Holster -- it allows a character to carry a compact pistol while inflicting penalties to tests that can discover it. The best sorts also provide quick-draw capability.

Video Games

 * Many characters in the Assassin's Creed series have hidden blades.
 * In Fallout: New Vegas, the player can hide certain weapons on their person when going into places where weapons are confiscated. With a high enough Sneak skill they can hide more kinds of weapons.