Kingdom Hearts Riddles III

[~Storm Ninja~]

okay, this is gonna be a little weird...

'tis a reign of destruction
all are killed save three
who stand alone against their foe
quick reflexes will save you faster
than anything else could
block, dodge, it's no use
if you can't master the ever-changing feild of battle
transform, or call in allies
it only matters if you can actually
catch him unawares
armed and dangerous
it should be expected
of a warrior of such a caliber
second to none, but to all as well

who is he?

there are very subtle hints in here, i hope this lasts for more than 5 minutes.