Damn I love it! Finally found a skeleton swordsman with pretty nice two-handed sword.
Also, I'm happy that you didn't remove the book, I like it.
@Edit: Using holy magic as undead isn't prohibited, it's just less practical. According to lore, channeling light makes one closer to light. Being closer to light, makes one's soul closer to body. When undead's soul is closer to his body, he feels more (both emotions and stimuli), which makes him feel pain. And yes, that's why holy spells hit undead so much - it makes them feel rotting tissues and maggots in their bodies. Undead priest/paladin is torturing themself.