My solution is to make mages overpowered.
Put it this way: When you have to go to lots of extra work to accomplish something successfully, it should be much, much more rewarding. Playing as a sniper and managing a headshot on someone is an instant-kill in Team Fortress 2, compared to firing rockets which does mild damage.
Make the mage the "expert" class. If you don't know how to play him, you will do miserably and get wrecked. If you're good at knowing the right spell to cast at the right time, you will decimate everyone. Conversely, make the fighter sort of an "equalizer", that you don't have to be supreme at to do well with.
Put it this way: When you have to go to lots of extra work to accomplish something successfully, it should be much, much more rewarding. Playing as a sniper and managing a headshot on someone is an instant-kill in Team Fortress 2, compared to firing rockets which does mild damage.
Make the mage the "expert" class. If you don't know how to play him, you will do miserably and get wrecked. If you're good at knowing the right spell to cast at the right time, you will decimate everyone. Conversely, make the fighter sort of an "equalizer", that you don't have to be supreme at to do well with.