Having to display your weapon as a warning to a perp is of no practical use. It will eventually lead to perps becoming more aggressive in an attempt to thwart legal carriers from having an element of surprise by starting the commission of their crimes armed & IN HAND. It also decreases the CCW holders opportunity to purge the gene pool greatly. Warning Shot? First shot into perp followed by LOUD STOP/HALT command. Pause. Second shot into the ground. That should satisfy all concerned.
One of the incidents that occurred to me happened like this. One 20 something knocked on door of house I was flipping and wanted to look at house "to tell his mother about it". I made 2 mistakes, I let him in and I didn't lock the door. Keeping him at 10 ft, he quickly became highly suspicious and shifted my right hand to my pistol (small of back holster). As he was running out of BS to say, the door opened and his buddy came in. They were exchanging looks and I knew I was seconds from an assault. I drew and told them to leave, they ran like hell. Had I shot 2 unarmed yutes at that point, I would have gone to jail, and I wasn't 100% certain of their intent until they ran without even saying a word.