Well thanks to all of you for these useful advices.
I'll have to think it over (and put my hands on my old copy of inquisitor which seems to have disappeared along with part of my witch hunter-necromunda collection, damned!)
I've read dark heresy lately and although a RPG, it has interesting background and "career" progression.
I'll be back once all this is all set up (it may take quite a while though, having little time for the beloved hobby)