A few bullets did get around or under the vest, enought to perforate his liver or whatever...So he was wounded, and pretty touch & go for a while, but I'm guessing that the monks used all their ancient arts to heal him, all those months he was in Bhutanepal
...That's not hard to understand...And he was still limping when Anna/Syd came to see him...
BTW, I thought it was so cool how Vaughn just went along with Anna's (terrible!!) masquerade, just let her think she was getting away with it...Anna is just not a social person, she hates men, and her knowledge of Vaughn & Sydney's relationship was non-existent...She made several telling mistakes (the kiss, the gaffe about Vaughn's eye color, the lack of emotion when she was telling him about Isabelle)...Vaughn is far from stupid, his favorite thing is to just listen and watch, and keep his mouth shut...He just let her make an ass of herself and then he lowered the boom...
"And for the record, you're a TERRIBLE KISSER!!!!"