The creature moves swiftly, and, uninjured, would have avoided his stroke, but its wounds but it just enough off balance that the swipe connected, not quite severing the head, but earning him a spray of something foul-smelling; likely, whatever this creature uses for blood. It continues to struggle feebly, though most of its movements are death spasms more than anything else, and it'll likely take a few more blows to actually kill it for good.