[SpongeBobTheDestoyer]

I don't remember for sure but he may have spell immunity- abjuration cast on himself. If that's the case then all abjuration spells won't work. Dispel magic, breach, pierce magic, etc. I recently learned that there is one dispelling type spell that is not an abjuration, Ruby Ray of Reversal. This spell is a life saver. You might have to cast another spell like secret word first to take care of his spell shield if he has one up. Then RRoR and breach to disable his weapon protections.

BTW don't knock yourself for not breezing through parts of this game. Probably most of the people who do breeze through have played it over and over again. Knowing how to use magic in this game is very important though.