I've always had the theory that we were to hand it back, at least for paladins. We, the players, aren't really what I would see as the 'ashbringer'. You have Arator there, a son of legends. You have Liandrin, you have a damn being of light there too, who is even the high commander of the army of light. The damn thing has its own ship to cruise in.
At the end of Legion, I've always had the theory that I am to hand the artifact to Arator, just seems more right.