Actor Chadwick Boseman spoke in detail about the Black Panther costume’s main capability thanks to being infused with vibranium: absorbing attacks from an opponent. He told EW:
The vibranium is a metal that is dynamic. It can change how it’s used. It’s not a liquid, but it has the ability to change shape and change form and still have its strength. … It’s not just about being durable, it has the ability to absorb energy. It’s not just like you hit it and it doesn’t take it. It has the ability to absorb the attack of another person and repel or respond to that attack. That’s part of the power.
While Wakanda being the source of vibranium wasn’t revealed until earlier this year in Avengers: Age of Ultron, we’ve seen since 2011’s Captain America: The First Avenger how powerful the substance is. Not only is Steve Rogers’ shield a good offensive weapn, being able to ricochet off surfaces perfectly, but it’s balanced defensively as well, like when Steve used it to cushion himself from a big fall. Heck, we’ve even seen it absorb blows from Thor's hammer Mjolnir and subsequently produce powerful shock waves. So the Black Panther suit will have these same absorbing abilities, meaning that even if you manage to punch him, it won’t do much good since the metal will just respond to the blow.
T’Challa will wear his vibranium suit in Captain America: Civil War when he comes to the United States to hunt down Bucky Barnes, a.k.a. Winter Soldier. Although he’s been described as the movie’s "third party," he’ll ally himself with Iron Man in order to track down Bucky for a crime the former HYDRA assassin has been framed for. Last week’s trailer showed the two of them fighting (or rather, just T’Challa roundhouse kicking Bucky in the face), and while Bucky’s metal arm is powerful, I suspect him punching T’Challa in kind with it won’t be effective if the Black Panther suit will just deflect the attack.
We’ll see Black Panther in action when Captain America: Civil War arrives on May 6, 2016, and if Captain America and Black Panther end up fighting each other, it will be interesting to see what happens when Steve’s shield makes contact with T’Challa’s costume. It’s like they say: fight fire with fire.