Three different phaser pistols. Lower left, TOS Phaser, top, Star Trek III Phaser, bottom right, Star Trek I and II phaser, though it never showed up in the first film. This one was designed to actually come apart...at the line. Like the original TV series phaser, you have phaser one. To increase the strength, you put it in the pistol grip and have phaser two. I believe the top one is designed that way also with a newer, more updated hand phaser one snapped in the top.
By the way, this is an updated pic of an earlier one. In the original I only had three, but since I did multiple Tricorders, I redid this incorporating my latest and some of my early work with the Pike's Laser gun and the TNG phaser...both very early in my Corel experience. I will modify them soon. Interesting point too...you notice that all the phasers from the original series on have that same design aspect...the long back, almost lobsided. At the time, not the conventional point and shoot look. They did maintain that even in the new movie which I did like. However I always felt that even though designed in the sixties, the original phaser can stand up to today's high tech sci fi designs. I don't understand why they didn't use them in the film...just one of my many gripes of that movie, even though I DID like it.