Iron Fist/Fallout 4

Iron Fist is a perk that can be unlocked in both Fallout 3 and Fallout 4.

Effects
The Iron Fist perk is a 5-ranked perk. With the first rank, punching attacks do 20% more damage. The second rank increases the damage bonus to 40%, and allows unarmed attacks to sometimes disarm your opponent. The third rank increases the bonus damage to 60%, and gives unarmed power attacks a chance to cripple an enemy's limb. The fourth rank increases the bonus damage to 80% and boosts the chance of crippling an enemy's limb with a power attack. The fifth and final rank increases unarmed attacks to do 100% more damage, and critical hit in V.A.T.S. will paralyze opponents.