Despite the title and apparent lead character, it seems to me the most important person in this movie is the female lead, and only from that perspective did I come to understand it. The movie is one of those classical China-desert movies with endless sands and hills, rocky settlements in places where you wonder how they survive. "Swordsman of Double Flag Town" is another with very similar settings. although I thought that a much better movie.
The title character here, Butcher, is basically a good bloke on the run, fastest sword in the west and all that but with the usual heart of gold. Crucially, he sees no path but his one of violent justice and necessary self-defence. In this he is contrasted heavily with the cowardly yet violent tavern-owner Gui. It is Gui's wife, "Pomegranate", who shows development and change.
There is the occasional flash of humour to stop the desert from drying out your interest completely. One of the best is where Butcher has just defeated two foes who take time out for a brief and hilarious conversation with one another before keeling over.
The ending will not satisfy everyone but, like I said, you have to reconsider it from her point of view. Over all the movie left me with only average satisfaction hence the rating. I am not disappointed to have watched it but would not put it on my list to see again.