Ummm... to state the obvious, if you are, for example, granting 4 PC's (+4/+4) to hit/dam, and 4 hit that round, 3 easily and 1 only because of your +4 to hit bonus, you are doing 3*4=12 + entire damage from the 4th hit that would have been a miss otherwise in DIRECT MELEE DAMAGE.
You are just...