Banes face is most likely extremely disfigured also. Thats what he means when he says the mask contains his pain. Mayb his pain is bc he was disfigured n his face is shattered. He means that the person will b disgustd horrifyd n shokd when they look upon whats left of his face. It protects his shatterd features. Also allows to breathe in a painkiller contained n distrubuted in the mask while securing facial muscle integrity

Bane's face is most likely extremely disfigured also. That's what he means when he says the mask contains his pain. Maybe his pain is because he was disfigured and his face is shattered. He knows that anyone who looks at what's left of his face will be disgusted, horrified and shocked. It protects his shattered features and allows him to breathe in a painkiller contained and distributed by the mask while securing facial muscle integrity.