Did you believe that Omnislash was the ultimate Limit Break in this game?
No, it isn't, it's actually Ungarmax.
I mean, think about it: Omnislash hits about 16 times or something, while Ungarmax pounds the enemies about 30 times!
Moreover, both of these Limit Breaks can be boosted to 9999 DMG per hit, and everyone knows that
9999*30 > 9999*16.

Actually, even the Highwind is superior; it's basically Ungarmax with different graphics.