Not that this could be implemented without work, but I think it would be fun and add a crazy weird new gameplay element.
Skill: Equip Change
Trained to some % of a stat
In the first melee round whatever minion has this trained to full effect will change equipment to a different set, for the rest of the fight.
Enchanters turning into walls, walls dropping heavy armor and becoming light melee tanks, etc. You would have to give up BL or archery, but the fun factor would make up for it :D