The new secret boss isn't a secret at all.

[Vani]

That would be awesome if it was Eraqus, but I doubt it is. Where would he get the coat from?

As for for Xemnas not weilding a keyblade, he is the Nobody of Xehanort, not Master Xehanort, the younger one that DiZ found. And young Xehanort did not weild a keyblade, so his Nobody didn't either.

it would be eraqus sentiment not eraqus. as to where he got the coat, perhaps he had some too. being paranoid of the darknss or whatever.