Ran into that too but in the other way (three magic, one physical). There are spells that break down physical armor (tentacle whip, decay, I think shackles of pain, etc) but I wouldn't change your mage. Some monsters are very good against physical and wimps versus magic so having a mage is quite valuable. I thought of trying an all physical group as well as an all magic group but haven't done so as of yet.
