Gosetsu got shot a few times from close range, probably tore a few muscles trying to hold the roof of a castle up long enough so everyone could escape, had said castle fall on him, nearly drowned and washed up on a deserted island with the person who tried to kill him in the first place.

The first of those things should have killed him, followed by an entire castle falling down on his head. But...you know, details. I wasn't unhappy with his survival though, even though he probably shouldn't have survived at all.