Being in combat and a boss throws up multiple defenses that counters your schools. How about the idea of being able to switch wands durring combat.
for instance being able to use two wands like in your primary and secondary schools or wands you have in your enventory that your able to correctly use, as well as taking a penality per switch, a accuracy hit, for switching for the first attempt (-30%) then a commulative pentality per switch there after, maybe a (-1 to -5%) accuacy hit thats additional to the -30%....