Hardedge

Hardedge is a greatsword. It gives the wielder an 80% increased chance of breaking a target's appendage(s).

Source
Hardedge can be purchased from the Culless Munitions in Lestallum, the Verinas Mart in Ravatogh, and from the Imperial vendor outside Steyliff Grove during Chapter 7 for 1,500 gil. It can also be found as a collectable at a wooden shack south of Pullmoor Haven in Duscae and in the Daurell Caverns dungeon. It can be sold back to shops for 750 gil.

Trivia

 * There are several weapons (including a pair of handguns) named Hardedge that appear throughout the Final Fantasy series.