Souba
From Final Fantasy Wiki
The Souba is a kind of weapon which appeared in Final Fantasy VII: Advent Children. It is the main weapon of Kadaj, leader of the Sephiroth's remnants who appear in the movie. The Souba is a katana with two reinforced parallel blades, set a small distance apart from each other, the intent of the design to trap an opponent's sword between them and disarm them. Despite being much smaller than the First Tsurugi, Kadaj is able to battle Cloud using the sword with no apparent handicap, using the sword's dual blades to also give it a wider striking range and more easily deflect Cloud's attacks than a more narrow sword would be able to.
The blade is lost in the ruins of Midgar during his final battle with Cloud, but after Kadaj reforms into Sephiroth and is subsequently defeated, it regenerates with him. Following his death in Aerith' Great Gospel Limit Break, both Kadaj and the sword vanish into the Lifestream.
Some of the Souba's replicas can be split into two katanas, but this feature has not been officially confirmed.
