It all comes down to where you want to go with the character in the long run, I think. I could totally see a character being "done", when his main motivation to go forward has been removed, and he can retire.
For an item like you described, I would probably not do anything mechanical as of yet. An aspect is enough. An item like that would feel like it would act much like a cursed item. You go to the end of the world, drop it into the deepest chasm of the ocean, and when you return home, the artifact is waiting on your nightstand. There is really nothing you can do to permanently get rid of it, it will just find you and stay with you.
I sort of have an image in my mind that could work in the long rung. It might be a little strange, but it should work. How about it isn't one item, but many. Like a lot. I'm thinking of magical items that the character is seeking out in order to incorporate them into his body and mind, in order to keep the vampire half to take over. An enchanted glass eye he puts into his socket, after removing his real eye, for example. Think tattoos of st. Giles turned to 11.
I've got this image of Thomas soulgaze in my mind. It would be similar for this character, but he would be able to turn his eye inwards to a similar scene, his inner self battling his inner demon, but he has control over it, and he can fight and restrain his demon by the magical items he links to his body, because they show up in this inner vision as well.
Over time, his powers would come from the items, not the vampire, as the hunger is bound inside his soul. The process could be slow, taking away hunger, taking away vampire powers, rephrasing powers as the reason the character has them changes, and so forth. Of course, the character would sort of become a freak of nature/magic over time, but I feel like that would be an interesting way to go. Or maybe even keep the hunger, but turn it into a different kind of hunger. The need to fuel the items with magic, for example.