Developed in antiquity, this weapon is nevertheless quite prevalent in the post-Great War wastelands.
Brass knuckles take the form of four linked metal rings in a shallow convex formation with a bumper attached to the concave face. The rings are slipped over a combatant's fingers with the bumper pressed into the palm of the hand. When a punch is thrown, the brass knuckles take the majority of the impact impulse, transferring much of the punch's kinetic energy to the target by way of the harder, smaller impacting surface of the metal knuckles. This drastically increases the likelihood of serious tissue disruption and bone damage.
Spiked knuckles are an easy replacement for brass knuckles in Fallout 3, being not much harder to find. Essentially just brass knuckles with spikes welded on to the impact plate, they deal slightly more damage as well.
Plunkett's Valid Points, a unique variant that has the lowest AP cost in the base game in addition to greater damage.