Hand phaser

A hand phaser is essentially a phaser pistol. Various models have appeared in Star Trek through the years.

TOS Hand Phasers

In the original Star Trek, the Federation has two types of hand phaser. "Phaser 1" is a small oblong device with an emitter on one end and fire controls on one of its largest surfaces. These controls include a firing button, a dial to change the setting, and a crystal meter, presumably for reading either the setting or the charge status or both. While such a weapon would not be easy to aim at any significant range, it is readily concealable.

"Phaser 2" is actually an add-on for Phaser 1. The device consists of a conventional handle and trigger arrangement (although shamefully lacking a trigger guard) with a larger beam emitter at the end and a niche on top into which a Phaser 1 fits. Presumably the Phaser 1's firing button is disabled when it is attached to a Phaser 2 handgrip, while the meter and adjustment dial function normally for the combined weapon. The Phaser 2 attachment also has a dial at the back which presumably allows the user to adjust the spread of the beam, a feature not seen on Phaser 1. Phaser 2 increases the power output of the weapon, and the combined device probably has greater energy reserves.