Who knows, but here is actually an interesting thing about the Odin FATE.
It appears that the person to land the killing blow on Odin has a slightly different ending screen for the FATE. And next time that Odin appears, he will bear the likeness of his slayer. (somewhere around these boards is the video of that happening, tiny, tiny Odin)

Perhaps that is something important to his nature, and this blond-haired man we see is not Odin himself but the one who was, technically, his last slayer, that allagan hero.