Well, that is an interesting resolution.
Vince fails in the fight against Stephan. In order to avoid anarchy consuming the world, Terik, makes an executive decision to live out life in a human body, remaining much of her godly abilities.
Vince's sacrifice, unasked, is to give up all his magic. You know, as much as I don't like this, I believe that given the choice - you remain dead and the world is thrown into anarchy-or- you return to Mace the love of your life, the world's balance is retained but you lose all your magic- Vince would have given up his magic. He is that kind of guy.