Defeating The Pain non-lethally will award you with the Hornet Stripe Camo which you can pick up on the platform he was on. As soon as the fight starts you'll have a good chance to take some shots at ...

As soon as the fight starts you'll have a good chance to take some shots at The Pain, depleting his health or stamina, whichever one you prefer. You can't damage The Pain while he's covered in hornets ...