WARNING: "Bane" spoilers below
The mask is an anesthetic dispenser. Without it, he's almost paralysed.
The comics say that it's Venom serum that makes him stronger.
In TDKR, it's anesthetic... which is also why he is so strong as he feels almost no pain at all with the mask.
If you notice in the scene where they capture Gordon, he has his top off and you see a scar down his spine from an injury he suffered at the hands of those prisoners when he helped Talia escape.
The mask is an anesthetic dispenser. Without it, he's almost paralysed.
The comics say that it's Venom serum that makes him stronger.
In TDKR, it's anesthetic... which is also why he is so strong as he feels almost no pain at all with the mask.
If you notice in the scene where they capture Gordon, he has his top off and you see a scar down his spine from an injury he suffered at the hands of those prisoners when he helped Talia escape.