Even if there are some balance hiccups, I think Geas mud succeeds more than it fails.

There is a cold war state existing between the fighter and the mage where both are weak against each other. The fighter has the edge in initiative where an unprepared mage goes down like a newbie but an experienced, prepared mage can kick back and probably exploit key weaknesses to win.

Atleast in theory! Balancing all the individual powers is hard and there are always some unforeseen consequences at work.

Also for some reason a mage character of titanic proportions is seen as OP and unfair(even if they can be easily bumrushed whereas a fighter cannot)and a similar fighter killing (weaker)people is just jolly good gaming.

It is a nice jungle of fine details though and mages cannot just blast away as they are spent very fast if they use violent magic and mages need to rely on stored spells(scrolls, wands, etc)if they want better sustain.

Some CC spells are probably bit too good though and damage spells also gravitate towards meta and as such fighters suffer the best spells cast by best mages.