This unusual weapon seems to be somewhat inspired by the indian bagh naka, a weapon designed to fit over the knuckles or be concealed against the palm and equipped with sharp blades designed to cut skin and muscle, and most probably inspired by the armament of big cats like tigers.
Like the bagh naka, this weapon is designed for close combat, and often associated with thieves, assassins and maniacs. This could be reflected in the claw being the weapon-of-choice of a mercenary ninja group.
In Gameplay Edit
It's the primary weapon of the Mosu Ninja, but only used if an enemy gets too close to them. The Mosu's variation of claw is comprised of four blades in parallel directions and held by a handle made from the connected blades. In combat the Mosu use it in combination with rapid kicks to keep enemies away.
See the Mosu Ninja page for the combat movelist.