Actually, being 'tainted' makes very little difference; some NPCs aren't very friendly, but it never held any of my chars back. But each to their own.
Mage or Knight Spirit magic... well, imo, Smite and Fortitude branches are both very good. The Celestial Smite spell is pretty near as good as having a Bow and arrows - except you need the mana for the spell and you don't with Ranged. Fortitude has the Healing spells, of course, so is very handy...
I would also be inclined to put some points into Tribal Protection, just to get Absorb Spirit - VERY useful when you are out of healing juice!
And Thought Lightning or Thought Ice.
Magic users are fine with fighting if you have a good character build. Give him/her One-Hand Melee if you don't like Ranged. That way you can have a shield to help with protection. Ok, I know it isn't PURE Mage; so, if you don't want to go that way, concentrate on Divine Protection branch!
I have a Mage in Oblivion trotting around dungeons in a pretty frock...
