After Wakanda's future king, T'Challa made an impressive debut in Captain America: Civil War his jaw-dropping vibranium suit put even Iron Man's armour to shame. But when Black Panther came out, the superhero's suit had undergone significant upgrades by Shuri, T'Challa's sister, who wanted it to be impenetrable and lend the Wakandian king the invincibility he needed as a warrior. But just as Tony Stark tinkered with his armour based on his past experiences, a new MCU-canon book The Wakanda Files reveals that Black Widow was the reason behind the Black Panther getting an upgraded suit.

Before the events of Black Panther, T'Challa had been in Germany, fighting alongside Iron Man to stop Captain America from escaping with Bucky Barnes as he believes that the former HYDRA agent had killed his father, T'Chaka. But during the major face-off, even as T'Challa gained the upper-hand against both Cap and Bucky combined, he was thwarted by the Black Widow electric projectile bites that incapacitated him. 

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Even though T'Challa had made amends with Captain America and went as far as to offer asylum to Barnes in Wakanda by the end of the film, a log by Shuri in The Wakanda Files shares that he was less than happy with the fact that Natasha Romanoff had overpowered him. The log states that as he expressed concerns over Black Widow's weapon's easily defeating him, Shuri took it upon herself to evaluate the extent of the projectile bites' powers and shared the same with T'Challa in a letter. 

"Your highness, we have evaluated the technology encountered in Berlin which was employed by the Black Widow," Shuri wrote. "Our findings conclude effects and recovery time are quite similar if not identical to a standard issue law enforcement stun gun."

She further noted that when Natasha attacked T'Challa with the weapons the "minimum settings were engaged" which reinforces that she had no plans of actually harming him. She only wanted to slow him down enough to let Cap and Bucky Barnes run away unscathed from the combined attack of the Black Panther and Iron Man.

"Should the highest setting of these devices be engaged and a prolonged exposure to high amperage current in experienced, side-effects could include permanent nerve damage, third-degree subdermal burns, loss of vision, even death," Shuri further added.

This additional observation means that even the lowest setting on the projectile bites managed to subdue the supposedly super-powerful vibranium suit of the Black Panther. It was a vulnerability that irked T'Challa and as shared by Shuri, he mentioned his annoyance over the same many times.

"Brother has mentioned on many occasions how he felt foolish that the Black widow's projectile bites were able to keep him from pursuing Rogers at the Berlin airport," Shuri reveals in The Wakanda Files. "The new nanotechnology and kinetic disbursement in his suit should prevent a repeat issue."

As MCU fans know, Black Panther's new, upgraded suit could absorb kinetic energy, harness it, and refocus it later as an offensive attack. So, if Black Widow have had another face-off with the Wakandian king, she would have seen her mighty weapons fail against his indestructible brand new suit. This was first reported by ComicBook.