i worked as a bouncer for 4 years and i've dabbled in a few different martial arts and actually trained quite a bit in krav maga but the only strike i ever actually used in an altercation was a good solid jab to the nose, the yes water, the vision is clouded by tears and pain, usually both hands immediately move to the face to protect it and you've now seriously improved your chances for flight if desired. the key is don't aim at the nose, aim for the back of the skull behind the nose. and believe me when i say it works the other way around too, i've lost more fights than i've won because i didn't react fast enough. lol
I'd rather have it and not need it than need it and not have it.