A cross face should not be thrown.That would make it an illegal or punishing move and any move that is done for punishment only is illegal. If used correctly it will turn an apposing wreastlers head away from single. A good crossface can be used to set up several moves to turn the apposing wrestler. And yes if done properly it will cause a great deal of Legal Discomfort. I have seen a number of wrestlers bloody their own nose refusing to yeild to a good crossface. God didn't make the nose cartilage stronger than the wrist.