Iron Fist

Iron Fist is a perk in Fallout 3, Fallout 4, Fallout 76 and Fallout 2d20.

Effects
Each time this perk is taken, it increases Unarmed damage by +5 points.

Bugs
Upon unlocking rank five, critical hits in V.A.T.S. while wearing power armor will no longer function; the Sole Survivor will simply stand idle while no animation is played or AP is consumed.

Effects
Iron Fist is a perk in the Nuclear Winter battle royale mode.
 * Nuclear Winter

Modifies weapons
Iron Fist affects the following weapons, as well as their unique variants:

Fallout 2d20
At rank 1, unarmed attacks inflict +1d6 damage. At rank 2, unarmed attacks also gain the Vicious damage effect.

After rank 1, the level requirement increases by 5.

Behind the scenes
The perk is may be a reference to the Marvel Comics character Iron Fist, whose chi-focusing abilities allow for powerful punches and attacks. This is further supported by the Fallout 4 version carrying the description,

Eisenfaust Puño de Hierro Poing de fer Стальной кулак Сталевий кулак 铁拳