I dont exclude the possibitly of it working... what i am thinking now that you (sort of) pointed it out, is that a mage can act as both melee and ranged char.
Im not refering to melee as warrior.... what i am trying to say is:
Your mage can be ranged (casting spells from a safe distance), as well as when the enemy comes into melee range (right up to your char), whip out the dagger / staff / whatever weapon and still clobber the monster a silly shot over the head.... (act as melee character), all while your archer is killing off a couple at the same time...