Whether it nerfs or not depends on actual implementation.
In HERO, normal attacks do STUN Damage, but do Body damage based on the numbers on the d6s you roll: 2-5's do 1Bod each, 6s do 2Bod each.
STUN-only attacks do only STUN damage, naturally.
Standard Killing Attacks do Body based on their dice rolls, and have a multiplier to determine STUN damage. Some do no STUN, though, if so designed.
In HERO, normal attacks do STUN Damage, but do Body damage based on the numbers on the d6s you roll: 2-5's do 1Bod each, 6s do 2Bod each.
STUN-only attacks do only STUN damage, naturally.
Standard Killing Attacks do Body based on their dice rolls, and have a multiplier to determine STUN damage. Some do no STUN, though, if so designed.