Thanks! Yes, it does seem that some of the skills need to be boosted, and others pulled back. I did a successful fire mage run today and, again, was able to coast to victory on Dominate and Freeze.
For Dominate, I could see having a duration as a way to bring it back into balance. Possibly it could have a maximum number of hitpoints which can be controlled at one time (currently, it makes encounters with big, scary high-HP monsters semi-trivial).
For Freeze, possibly frozen enemies could be immune or resistant to damage. Logically, I don't know whether it makes more sense to take more, less, or the same when encased in a block of ice. From what I can tell, it's main usage is easily killing single target enemies, not freezing them in place for any other tactical reason.
Alternately, one could boost the damage output of Tornado, Fire Sphere, etc.
Another issue is that STR and DEX classes don't have extremely powerful skills to cross-class into. Maybe Strafe Attack and Bear Trap would count?