Arsenal Attire

There are times when even the most awkward looking clothing will turn out to be a lethal weapon.

The princess in the ball gown?

She spins and a fringe of razorblades flips out.

That guy in the top hat?

It's made of magical caterpillar silk and will block a gunshot or cut your head off.

The dancer 'wearing' nothing but fans?

She flips them backward and they will decapitate you.

The guy eating soup in the truck stop?

His bandana is made of armor plates that will stop a bullet and/or break your face.

Do you ever wonder why they call them 'stiletto' heels?

Many heroes will wear armor and weapons that are invisible to casual observation because they look like part of their normal clothing. This has many advantages, not the least of which is being able to take them places where weapons are not normally allowed.

This kind of double purpose clothes are a common hallmark of a Badass.

This trope is sometimes a Sub-Trope of Clothes Make the Superman and Clothing Combat, but not always. It is often a Super-Trope to Hat of Power.Weaponized Headgear and Sword Cane are Subtropes.

Anime and Manga

 * Gunsmith Cats: Bean Bandit's outfits.
 * Robert Edward O. Speedwagon from JoJo's Bizarre Adventure has a bowler hat with blades in the brim (in an obvious reference to James Bond's OddJob).

Comic Books

 * Lady Killer from The Strangers in The Ultraverse was a superhero who was also a fashion designer. Every part of her costume could be used as a weapon.
 * Daredevil uses a billy club that conceals a grapple, which in his civilian identity of Matt Murdock, converts into a harmless looking blind man's cane.

Fan Works

 * In the Sailor Moon/Ranma ½ crossover Relatively Absent, female!Ranma -- after assuming the mantle of Guardian Khronos -- discovers that many of the despised Frills of Justice on her Sailor Fuku-styled uniform actually hide or can be (possibly deliberately) repurposed as weapons.

Film

 * The razor-brimmed bowler hat worn by Oddjob (played by Harold Sakata) in the James Bond film Goldfinger.
 * In the 1982 film Ninja Strikes Back (aka Bruce contre-attaque), Harold Sakata appears as another villainous character who also has a hat-weapon.
 * "Random Task", a villainous minion who throws his shoe as a weapon, from Austin Powers: International Man of Mystery.
 * Similarly, Molok from the Italian parody film Two Mafiosi Against Goldfinger throws a deadly shoe to kill his opponents.
 * In the parody film A Fistful of Yen from Kentucky Fried Movie, Dr. Klahn's army trains by throwing razored bowler hats at a statue.
 * In The Dark Knight, the Joker wears shoes that have a spring-loaded knife built into the sole.

Literature

 * In The Looking Glass Wars, the entire Millenary, but Hatter Madigan's wardrobe in particular.
 * Discworld:
 * Adorabell Dearhart, AKA "Spike", AKA "Killer", has stiletto heels that can punch through two reinforced layers of cured leather and a human foot and still embed themselves into an oak floor board.
 * When he was a street ruffian in his youth, Sam Vimes' butler Wilkins used to own a hat with sharpened pennies sewn into the brim for fighting.

Live-Action TV

 * In one episode of The Beverly Hillbillies Jethro coats his own hat with metal to turn it into a throwing weapon after watching a James Bond movie.

Tabletop Games

 * Shadowrun. The 2nd Edition supplement The Neo-Anarchists' Guide to Real Life had a section dedicated to armor and weapons disguised as clothing. They included the Barton Arms Bracer (a gun disguised as a piece of jewelry) and the Barton Arms Gun Cane (a cane that can fire a bullet). And a variety of fashion houses (Armante, Mortimer of London, Vashon Island and Zoe) have formal wear that could stop a bullet.
 * Dungeons & Dragons : Monks; everything they wear can be used as a weapon.
 * In the Forgotten Realms, rogues can wear "bladeboots", footwear with spring-loaded daggers built into the soles.

Video Games
": He's covered from head to toe in weaponry. Like a rainbow apocalypse.
 * in Kid Icarus: Uprising.
 * I prefer to think of it as my devastation ensemble. I only wear it for very special occasions. You know, weddings, armageddons..."

Web Comics

 * In Schlock Mercenary, the standard uniform for Tagon's Toughs is actually nanofiber armor with a deployable breathmask and allows antigrav flight as well.

Western Animation

 * In the episode "On Her Majesty's Sewer Service" of The Super Mario Bros. Super Show! (a James Bond parody), Mouser basically becomes Oddjob, complete with a bowler hat thrown as a weapon (although it acts as a bludgeon, not a cutting weapon).

Real Life

 * The Asiatic practice of making "weighted sleeves".
 * Ninjas did this sort of thing constantly.
 * Agents of the KGB were known to wear shoes with spring-loaded blades that could be deployed by clicking their heels together.