The kar'takin was a short polearm with a straight-edged blade and a stabbing point, favored by the Jem'Hadar for hand-to-hand combat.
They were used by Dominion and Starfleet forces in the assault on Vandros IV in 2372. (DS9: "To the Death")
During the Dominion War, captured kar'takins were kept aboard Klingon ships for training purposes. In 2374, Worf introduced this weapon to his son Alexander, attacking him with it as part of a training exercise. (DS9: "Sons and Daughters")
A kar'takin was displayed on the wall, among the collection previously owned by Kerner Hauze, alongside a lirpa, ushaan-tor, bat'leth, and mek'leth. (LD: "Kayshon, His Eyes Open")
The kar'takin was designed by Dan Curry. (Star Trek: The Artistry of Dan Curry, p. 114)
The character Taran'atar, who was introduced in Avatar, possesses a kar'takin that he uses in combat.