I haven't had time to finish reading this (I've read Parts 1 and 2) but think the idea of Xander seeking training from Giles an excellent one. His fighting skills (along with other character's acquisition of welding, mining, languages etc)certainly went from nil to more-than-adequate with no explanation from ME. Your Giles voice is spot on, as is Xander's examination of the inadequacies he finds in himself and his family relationships.