back in exile with six characters i had 2 tanks, one archer and 1 mage, 1 priest, and 1 mage/priest
now it was true - it was the casters that did alot of the work.
however i found tha all the skills that the tanks could provide were also just as useful, in particular potion making. they were stocked heavily with potions, and also were VERY useful with their attack buffs/debuffs.
posion potion on sword saved me many times over when fighting more resistant enimies.
i wouldnt mind to see status enducing , or special effect spells on warriors - basically things that mages dont normally do
like coating their weapon with poison, or stunning the other character with their strike, or adding debuffs to their attack.
something like.. an active skill, which would have a passive effect.
this way you dont get the problem of fighters taking over, because most priests/mages rely on their active effects, with active skills.
purely passive skills simply add no intensity - assassination, riposte, parry etc. - they are just there.
but passive skills which can be activated <poison, debuffs to attack, etc.> would definately fit the line much better.