Winter Soldier's Prosthetic Arm

"You have a metal arm? That is awesome, dude!"

- Spider-Man to Winter Soldier

Winter Soldier's Prosthetic Arm is a cybernetic implant attached to the Winter Soldier's body to be used in place of his missing left arm.

History
Following Bucky Barnes' fall from Arnim Zola's speeding train, he suffered injuries that included the loss of his left arm. The prosthetic arm was only a portion of the reconstruction efforts HYDRA used in turning Barnes into their deadly assassin. The construction of the arm presumably took place in secret HYDRA facilities in the Soviet Union, following World War II. With the communist red star imprinted on the arm, the brainwashed Barnes eventually became known as the Winter Soldier.

During his fight with Captain America in Washington, D.C. following his attempt to kill Nick Fury, the Winter Soldier's arm was damaged by Captain America's Shield. The arm, which is at least partially mechanical, was repaired later by HYDRA doctors in the Ideal Federal Savings Bank, a HYDRA facility run by Alexander Pierce. Barnes later used the arm to rescue Rogers from drowning in the Potomac River.

Steve Rogers and Sam Wilson eventually trapped/tracked Barnes in a remote location, where his prosthetic arm was caught in a large vise.

Capabilities
The bionic arm gives him enhanced strength superior to that of Captain America. The Winter Soldier was able to rip open a S.H.I.E.L.D. armor SUV, rip apart Falcon's EXO-7 suit, and smash concrete by punching it. With his bionic arm supporting his already enhanced natural strength, the Winter Soldier was able to overpower Captain America in a fight.