Hey I've been looking for a martial arts movie I saw when I was a kid, it was about a man who fought with a spear. He found a young kid in a village who was a simple thief, they both got stuck together in a journey. In one scene the lead character got cut or something in the back so he was bleeding and he made the kid jump on his back to stop the bleeding while he was fighting against some enemies. Don't know what more to say but the lead character had long hair and white outfit and the kid had greyish outfit I think.

sounds abit like a jet li movie called - legend of the red dragon here's a clip which is close to your description

http://www.youtube.com/watch?v=swGowwlrneQ