I like the story Clint Smith at Thunder Ranch tells about taking some LEO guys through the Terminator (a shoot house) at night in Defensive Handgun III where all the participants were using simunitions. The cop comes upon Pete. Pete is the guy at TR responsible for all of the range physical plant sort of upkeep but also does double duty as a bad guy for classes like the DHIII. The cop locates Pete and immediately blinds him with his mega powerful Surefire night sun tactical ninja light (Clint Smith's description, not mine). While this is happening, the cop is giving orders to Pete who he sees is suffering from the light and has raised his hand to shield his eyes. Keep in mind, this is all happening fairly quickly in just a matter of a few seconds. The cop is thinking that Pete is capitulating. In the instant Pete has shielded his eyes from the glare, he is now able to see the cop just fine from all of the reflected light. Pete's raised hand was apparently enough of a visual distraction that the cop never saw Pete shooting him until after he was shot 3 times in the chest. Since it was simunitions, nobody was actually hurt, except maybe the cop's ego. So much for the light beam being a "weapon."
The lesson from all this is simple. A light is a tool, but don't count on it as a weapon based on the amount of light it projects. The supposed blinding effects can be very quickly defeated as simply as by shielding one's eyes with one hand. While you are blinding a person, don't count on the light as providing you cover. It doesn't. At best is provides poor concealment where the person being blinded can't quite tell where you are behind the light but knows you are close by (within arm's reach).
You know, if you use a light and somebody gives up or stops fighting because of the light, that is great. HOWEVER, under NO circumstances should you ever deploy a beam of light from a handheld or weapon mounted light and expect it to perform as a weapon. The weapon is easily defeated. It is not a good weapon and it certainly will do nothing to stop the person from shooting if they want to shoot at you. They may not be able to see anything but the light, but by golly you are going to be somewhere near that light and in very short order and with never seeing you, the bad guy can shoot you because he knows you are close to the light if not just directly behind it.