As its appearance implies, the Ray Gun is a one-handed pistol, meaning players can dual wield two of the same weapon, or hold a different item (shield, dagger, etc) at the same time as it.
The Ray Gun fires a unique green laser projectile that travels at an average speed in an oscillating 'wave' path in the direction fired. While this makes it harder to hit smaller targets, this special firing pattern makes the weapon very effective against larger targets such as bosses, as the projectiles suffer no inaccuracy or drop over distance otherwise.
The Ray Gun has a fire time of 0.2 seconds (5 shots per second) and a base DPS of 16.25, producing a base shot damage of 3.25.
When upgraded at a Weapon Upgrade Anvil to tier 6, the Ray Gun's base DPS rises to 22.75, producing a new base shot damage of 4.55; also, the Ray Gun itself takes on a new appearance, shown below.
Aside from the gold star next to the name and the boost in performance, no other changes occur.