That's correct, unfortunately, the attribute system in D:OS 2 is designed so that functioning equally well as a physical fighter and a caster means you are fighting half as well as someone specializing in either field. I guess the closest you come to a functional Battlemage is by going Lone Wolf.
Well, perhaps... but I was trying not to discuss this in terms of practicality, only concept-wise. Since it sounds like the OP is new to the game, I didn't want to discourage them from certain playstyles or trying things out right off the bat.