Warning! This post contains SPOILERS for What If…? Season 3, episode 3

Bucky Barnes’ iconic metal arm accomplishes an unprecedented feat of power in the MCU’s What If…? season 3 episode 3. What If…? season 3 presents a final wave of alternate timelines where several events take place much differently than in the MCU’s main universe. From Hydra failing to steal the Super Soldier serum from the Starks in 1991 to the Avengers building mechas to fight kaiju Hulks, What If…? season 3 shows both how lucky and unlucky the MCU’s Earth-616 has been in comparison to other realities in the Sacred Timeline.

What If…? season 3 episode 3, What If… Red Guardian Stopped Winter Soldier?, shows what would have happened if Alexei Shostakov a.k.a. Red Guardian had intervened in the Winter Soldier’s infamous 1991 mission. Although Red Guardian arrives late to save Howard and Maria Stark, he manages to stop Bucky Barnes from stealing the Super Soldier serum. What’s more, Red Guardian neutralizes the Winter Soldier’s programming with his charisma alone and joins forces with him to escape SHIELD, fighting none other than Bill Foster a.k.a. Goliath along the way.

Bucky’s Vibranium Arm Is One Of The MCU’s Coolest Artefacts

Bucky Barnes’ Two Bionic Arms Are Incredibly Powerful MCU Weapons

Bucky Barnes’ injuries from falling off a train allowed Hydra to create an incredibly powerful weapon. Taking advantage of Bucky’s amputated left arm, Hydra built a state-of-the-art, ultra-strong, and bulletproof arm made of Titanium that made the Winter Soldier almost unstoppable. Bucky’s original Titanium arm was strong enough to stop Captain America’s shield effortlessly. Yet, the vibranium arm that the Wakandans gifted Bucky after the events of Captain America: Civil War is even more powerful than the original, as it’s virtually indestructible and absorbs vibrations, meaning that Bucky is less affected by the momentum of the attacks he gives or receives.

What If Season 3 Shows How Powerful Bucky’s Arm Is

The Winter Soldier’s Arm Can Knock Out A Giant

In What If…? season 3 episode 3, Bill Foster corners Red Guardian and the Winter Soldier outside a casino in Las Vegas. Foster activates his suit’s size-shifting capabilities to transform into the giant Goliath. Bucky almost breaks Goliath’s ankle with a punch from his bionic arm, and Red Guardian then launches Bucky into the giant hero’s face, allowing Bucky to knock out Goliath with a single punch. Considering it took Spider-Man, Vision, Iron Man, and War Machine’s combined efforts to knock down Giant-Man in Captain America: Civil War, Bucky’s feat in What If…? season 3 episode 3 is nothing short of impressive.

Before knocking Goliath out, the Winter Soldier also displays his metal arm’s versatility in other moments throughout What If…? season 3 episode 3. For instance, Bucky saves Red Guardian from a barrage of Obadiah Stane’s gunshots, slides down a building while carrying Red Guardian, and takes the whole impact from a police van crashing into him — all using his metal arm, and aided by his super strength, speed, and reflexes. Even though the Winter Soldier’s arm doesn’t have a vibranium enhancement in What If…? season 3 episode 3, it’s still an extremely powerful and multifaceted MCU weapon.