...Considering how much loot is granted for their efforts, plus the mental trauma and serious internal injuries gained from adventuring, compounded by the fact that nothing will be more awesome than killing what is basically a god (very common in both western and eastern RPGS), and I think it's safe to say that yes, they do retire after that point.
...Hmm. I think you could get a campagin out of that.
I like it. It helps it looks like he's about to dash off into the sunset with it.
Although the hand holding the sword look a little borked, it really needs a thumb of some sort.