One victorious moment for Black Widow in Captain America: Civil War could change the way the Marvel Cinematic Universe depicts one of its most durable materials. Although Black Widow’s superpowers in the comics are comparable to Captain America’s, thanks to a Soviet version of the Super Soldier Formula, her MCU counterpart credibly stands alongside The Avengers’ heaviest hitters simply through skill, tactics, and potent gear. Civil War puts this to the test, putting Black Widow on Iron Man’s Avengers team and pitting her against powerful former allies.

Civil War also introduces T’Challa – the Black Panther – to the MCU, portraying him as another one of the franchise’s most formidable heroes. Like his comic counterpart, Black Panther’s physical abilities are greatly enhanced by Wakanda’s heart-shaped herb, but – thanks to the advanced technology of his home nation – Black Panther also uses a variety of gadgets. This, most notably, includes his costume, which is made of the highly-durable material known as vibranium, the same material as Captain America’s shield. As the MCU’s Wakandan lore has been delved into, so too have the applications of vibranium, yet the material is not invincible.

Black Widow Discovered Vibranium’s Weakness 8 Years Ago

During the main action set piece of Civil War – the airport fight – Black Widow betrays Stark’s team and helps Captain America and Bucky escape. As the two former opponents flee the airport in a Quinjet, Black Widow impedes Black Panther from pursuing the duo, firing taser discs at him from her gauntlets. Surprisingly, the projectiles work, with repeated hits stunning Black Panther long enough for Steve and Bucky to take off, though Black Panther does manage to plant a tracker on the Quinjet at the last moment.

Black Widow’s gauntlets and taser discs are originally Red Room weapons, but they’ve likely been upgraded by SHIELD and Tony Stark. Romanoff’s taser discs are shown to instantly render ordinary humans unconscious in most cases, so while Black Panther’s vibranium suit did offer a significant degree of protection against them, repeated hits still effectively slowed him down. Very few weapons can affect vibranium, with Thanos’s sword – which might have been made of Uru like Mjolnir and Stormbreaker – notably breaking Captain America’s shield in Avengers: Endgame, electricity seems to be one of vibranium’s few weaknesses.

How Vibranium’s MCU Weakness Totally Changes The Franchise

This weakness makes sense since vibranium is a metal and thus conducts electricity. Despite being one of the most durable materials in the MCU, it may not offer any enhanced protection against electricity for this reason. Black Widow’s taser discs are highly effective against ordinary human opponents, but T’Challa had similar superpowers to Captain America, which might have explained why he was only slowed down by multiple taser discs instead of being knocked out by one. More intense and repeated electrical attacks, however, could have fully incapacitated Black Panther.

Although T’Challa is deceased in the MCU, his younger sister – Shuri – is now the new Black Panther, using a similar vibranium suit and possessing the same superpowers. Any of Shuri’s potential adversaries could potentially exploit this weakness, using electricity-based attacks to impede or even incapacitate her. Sam Wilson – now the new Captain America – also wears a vibranium suit (gifted to him by Wakanda) but given his lack of superpowers, he might be even more vulnerable to electricity. Unlike rare cosmic weapons like Thanos’s sword, electrical weapons are fairly easy to obtain or design in the MCU.

Why The MCU May Never Acknowledge Vibranium’s Civil War Weakness Again

For better or worse, the relative mundanity of electrical weaponry could lead to this vibranium weakness never being exploited again. Vibranium and the heroes who use it typically battle powerful supervillains and electrical weapons could simply be too easy to obtain for conventional criminals and enforcers, who are not meant to threaten heroes like Black Panther and Captain America. Of course, there are ways for vibranium’s vulnerability to electricity to return in future MCU properties. The most obvious is through Yelena Belova, who has effectively succeeded Natasha Romanoff as the new Black Widow.

Belova uses the same Red Room weaponry as her adopted sister, giving her a potential advantage against both Black Panther and Captain America. MCU characters with electrokinetic abilities, such as a new version of Electro, could be introduced and potentially challenge the vibranium-equipped heroes as well. While vibranium’s weakness is unlikely to appear after Captain America: Civil War, the MCU could reuse it under the right circumstances.