I have my DK as a warrior and my hero as an archer, though could have done that the other way around.

Stop boosting strength (except for equipment requirements) until you get your agility up. Your chance to hit and be hit are probably not very good (check the trophy list). Also, since you are neglecting survival and speed your initiative is not going to be very good, nor is your evasion or hit rate. Basically, the enemy hits first, faster and more accurately, while you swing less often, miss more often and take longer to recover from attacks.