I think he'd be the type of person who wouldn't want to give himself another reason to feel like a horrible person. After all, he's very good at torturing himself over past deeds. I have to agree that he's probably too strict on himself to have a vice. Perhaps he has an occassional drink but I don't think that counts as a vice. He's got too much of a Bushido-like outlook on life and living to bother with vices IMHO.