Why does the laser seem to just end after a measly half a mile? On flat land, the horizon gets in the way at 7km's so if its true, the light should go on for a much longer distance

Even if you could make that thing into a lightsabre it would only be the size of a letter opener.

Lets analyse what has been told.

1) Your friend is getting a lightsaber
2) It can go for 120 miles
3) It shoots down airplanes
4) It easily burns stuff
5) Burns your eye at a certain angle.

Dude, does that make sense to you? lol

Totally makes me wish I had $1000 to spend on a laser to point at stars.

I've never taken a class in astronomy, but I'm pretty sure that you can use them as a pointer outside when not projecting onto a solid object. If there's enough moisture/stuff in the atmosphere it'll scatter off all the random particles (think how you can see the path of a movie projector's light because it scatters off the dust in the air) and make it visible in all directions.

In a Vacuum, it'll go on forever. But Earth (thankfully) does not have a vacuum on its surface. As such, the light will be scattered by particles in the atmosphere. This effect becomes much more extreme as distances increase.