If someone is going to use a light as a defense and that person was intending you harm from the gate (or the light might even result in provoking harm when it wasn't going to be the case to begin with), the light is just going to **** him off more and probably result in you getting the crap kicked out of you worse than if you hadn't done it, plus after he kicks your ***, he will probably steal your flashlight!
I can picture a guy who owns one of those multi functional Fenix lights, telling the assaulter to wait a sec while he's finding the right mode to shine at him. LOL
Or picturing some paranoid dude who always walks around at night with a flashlight in his hands waiting for someone to pop out of the bushes so he can shine the light in his face. Assaults don't happen that way. They happen when you're least expecting it or prepared for it. Surely no time to react in a split second to reach in your pocket and pull out a flashlight.
If my wife got confronted like that, I would want her to run like hell and scream bloody murder. I wouldn't tell her to reach into her purse, pull out her flashlight and shine it in the dude's face.
These are flashlights guys. I know we like to dream up all this stuff we're going to do with them, but having one in your pocket doesn't turn you into Clark Kent.