It's a laser, all you have to do is wave it around in a crowd you'll eventually hit people. Pilots get hit with them all the time because people think it's funny to point it at airplanes. People are doing this with much lower power lasers like 5mw. Even those will cause eye damage at close range, and eye strain/temp blindness at far range.
Sun glasses won't protect you from that, you need special laser grade glasses. Even refraction from surfaces can be dangerous if it's powerful enough. These things have applications as hobby etc but they need to be respected as being very dangerous.
Indeed, i own 4 pairs of protective eye wear to cover the whole spectrum and a few lasers over the 1W range. Safety is a top concern when operating them. 5mw though is safe even at close range.
I think what most people miss is its going to be hard to make a laser weapon because its almost impossible to focus the beam in a perfectly straight line and even if you do thats not good enough you want pinpoint focus on the target, there is always a focus point and thats where most of the energy is focused.
For example lets say i took one of my 1w lasers and focused it at 30 feet. It would ignite paper pretty easily at that distance with a focused beam. But at say 10 feet, or 50 feet, it wouldnt even get it warm, not enough power focused at those distances.
To militarize lasers you would need to have optics that continually shift the focus distance to match the target distance, and we are talking very fine precision optics here that likely wouldnt survive being banged around on the battlefield.
Not to mention the power source you would need for high powered lasers would be beackpack sized or larger perhaps even vehicle mounted.