Combat Haircomb

Women get all the best Hidden Weapons. A woman with a Combat Haircomb has an ornamental comb or pin to fasten her hair that is also a dagger or other sharp implement. It may be inside a sheath, or the hair itself may serve to hide the blade. It's very popular for spies and assassins as well as undercover warriors who need to blend in to high society functions.

In a pinch, chopstick-style plain wood hair pins can be used this way. Another variant is to use a big brush comb and use the handle to hide a weapon or as a blade. In rare cases, it's an actual comb, albeit with poison tips.

See also Slipknot Ponytail and Victoria's Secret Compartment.

Anime and Manga

 * Komachi from Naruto uses her kanzashi as weapons.
 * Yoko from Tengen Toppa Gurren Lagann uses two needles that serve as her hairpins to stab Adiane's scorpion tail

Film

 * The seeresses in Immortals had one used to break out of captivity.
 * A character in Leprechaun: In the Hood is killed by an afro pick to the throat.
 * The Three Musketeers 1973. While fighting Constance Bonacieux over the diamond-studded necklace, Milady pulls a ornamental hairpin out of her hair and uses it as a weapon.
 * A male example is the title character of Undercover Brother, who uses his afro picks as throwing knives.
 * Sherlock Holmes. Irene Adler, at least in the trailer (the scenes never made it into the movie).

Live Action TV

 * Buffy the Vampire Slayer. Buffy runs into evil vampire Angelus and draws a small stake she was holding her hair bun in place with, Shaking Her Hair Loose in the process. Angelus promptly quips, "Why, Ms. Summers! You're beautiful!"

Literature

 * Conina the barbarian hairdresser, in Terry Pratchett's Sourcery. She is the daughter of Cohen the Barbarian ("wholesale slaughter") so has no choice than to accept destiny as a barbarian warrior. But what she really wants is to own a hairdressing salon. In between bouts of sickening violence, she keeps her hand in by doing hairdo's. Sometimes combs and scissors become lethal weapons in her hands...
 * In The Gardella Vampire Chronicles, Victoria's hairdresser hides her stakes within her hairdos, for easy access.

Video Games

 * Red XIII from Final Fantasy VII is a good example of this.

Western Animation

 * The Tangle Web Comb on Xiaolin Showdown turns into a bunch of strings that can be used to bind the enemies.
 * The Johnny Bravo episode "Bravo, James Bravo" (a James Bond parody) had several spy gadgets, including the bomb haircomb -- one wave would arm it, another would disarm it. After getting it, Johnny immediately proceeds to rapidly comb his hair, sending his higher-ups into a panic. It doesn't explode though, because he's just that good at combing.

Real Life

 * Real-life Geisha Iwasaki Mineko wrote in her autobiography Geisha: a Life/Geisha of Gion that geisha occasionally used their kanzashi (hair ornaments) to defend themselves or their clients from assault.
 * In feudal Japan, the poisoned hairpin was a standard weapon for kunoichi (female assassins).
 * This.