ODIN

[Elexia]

Baron's king did in FFIV. Just sayin...

That wasn't fully explained either, since there's no allusions toward Odin at all in FFIV up until that point so like FFV, was just SE throwing Odin into the game. It's very unlikely he turns into Odin as there's no allusions in the lore that states people can be Primals.

Unlike XI where we know Garuda, Shiva and Ramuh were beings other than Avatars until Altana basically made them one, we learned that early into the game's lifespan and lore, so unless there's hidden lore somewhere that states people can turn into Primals, then the theory that he's Odin could hold some meaning.

Aether can do some strange things..but I really don't think making them a god tier Primal is one of it..or us using anima would basically give us means of being a god tier primal as well.