Christopher Nolan on Bane's uniform.
"Bane dresses in Military fashion. He leads a band of fanatical mercenaries who have done all kinds of horrible things and end up in Gotham. One of the influences on the script was Charles Dickens' A Tale of Two Cities, and with this overcoat, we wanted to infuse the romanticism of the French Revolution mixed with the World War II functionality. The essence of Bane is military power and brute force combine with revolutionary fervor.
Costume designer Lindy Hemming combined modern military gear with more old-fashioned materials like leather to give Bane's outfit the utilitarian, proactive quality he needs. He's always ready to fight."
The director also talked about the functionality of Bane's mask.
"Bane is someone ravaged by pain from a trauma suffered long ago. And the mask dispenses a type of anesthetic that keeps his pain jus below he threshold so he can function. The fearsomeness of intent and intelligence Hardy conveys just through his eyes is dazzling. But we've taken one of the most distinctive mouths in the movie business and covered it up for the entire film."