if you can keep it on his eyes.
That would be the key. In a darkened theater, getting a lot of light on the subject would be easier to accomplish especially if the broad beam of a powerful light could be coupled with a strobe.
I am not aware of any small handheld broad beam lasers. Might be interesting if a fairly powerful laser could be incorporated into the basic flashlight and bore sighted with the main tube. Might be that would allow one to quickly acquire the target with the flashlight in a darkened theater.