I know I have posted this a few times before if you have read my previous messages but I have a better idea for it this time.
The idea is......... Shields! ones you hold in your hand.
These shields would all be school only and focus on only resistance. For instance, a few that aren't as good could be bought and better ones are found. The better DS shields would be Lvl 50+ only and could be plus 30% resist to your class. I don't think there would be much a problem with someone getting 70% resist to their class as some higher leveled mobs have 70% and more.