I used to be an adventurer like you, until I took an arrow in the knee...
Can someone explain this to me?
He's like a crappy tight end who never made the bench slot on the A team. Instead of admitting that he svcked in his position, he tells the tale of how his bad knees ruined his chances to be an NFL star. So, for all we know, he never actually took an arrow to the knee. He just sees a bad @ss adventurer and wants to pull the old, "hey junior, I was just like you, but..." line. Guards aren't immune to narcissism.