All full-blooded Tarkatans are born with one thing under their arms: these are the Tarkatan Blades. They span approximately four feet. Baraka uses them in all of his Mortal Kombat appearances to perform all his special moves as well as quickly slicing through all who stand in his way. The signature weapon of the Tarkatan race first made its debut in Mortal Kombat II, and later was featured as a collectible Relic under the name "Baraka's Blade" within the Konquest mode of Mortal Kombat: Armageddon.
They are made into his weapon fighting style in Mortal Kombat: Deception, and remain that in Unchained and Armageddon.
In those three games, every time Baraka starts a round after losing the previous one, if he's laying with his back to the ground, he will lift himself extracting the blades, causing them to be his first fighting style in the next round, instead of Silat.
Erron Black is able to use a detached Tarkatan blade in Mortal Kombat X, exclusively in his Outlaw variation, fashioned from a severed and skeletal Tarkartan arm, making him the first non-Tarkatan character in the series to use one.
In addition, a guest character in Mortal Kombat X, the Alien, has retractable blades in its arms. This is because Xenomorphs take on the DNA traits of whatever species they impregnate; this particular Xenomorph was born from a Tarkatan. Unlike typical Tarkatan Blades however, the Alien's are segmented.