I'm alright with using your template, I doubt my drawing skills are up to par and I'm a perfectionist so it's going to take a long time for me to get the head right. My guy will probably have two appearances, cause I'm thinking he's going to be a well known general from the army so he has to take extra lengths to disguise himself, that also means that his treason to the demons will be much more notable. 

 I like the idea of custom weapons, perhaps something that matches their style and perhaps is the embodiment of themselves. So superhuman strength, nothing too crazy, healing ability? Immunity to poisons? Any possible abilities? Longevity? I would assume immortality unless they die.