We all agree that phasers are cool as well as iconic. They can heat rocks, stun aliens, or vaporize them with instant incineration. But they are still weapons and should be treated as such. I'm sure Starfleet basic training instills safe-handling principles when it comes to managing these kinds of devices such as 1) always assuming they're charged, 2) always pointing them in the safest direction, 3) always keeping the finger off the trigger...

...but wait, how many times did practically everyone in Starfleet violate this last rule? Kirk sure did more times than I can count. And why do phasers not have a trigger guard? Are there any internal safety mechanisms or can someone accidentally bump into a security officer, hit his phaser trigger, and zap him right then and there? Perhaps a red shirt can demonstrate this. They're there to take one for the team anyway.

In TNG, the phaser trigger is on the top panel. What happens if someone dropped one of these suckers on the floor? Would there be an unintended discharge, or do they contain safety mechanisms to ensure that a beam is emitted only if a living digit is pressed on it or intentionally pre-programmed?

The nice advantage of a phaser, of course, is the complete lack of recoil, unless you're in the new alternate timeline created after Nero arrived in front of the Kelvin.