The Kzinti phaser was a hand-held weapon used by the Kzinti during the 23rd century. It had a stun setting which temporarily knocked its victim to the ground.
The crew of the Traitor's Claw used these weapons against Hikaru Sulu, Spock, and Uhura on a planet in the Beta Lyrae system, although the Kzinti were prohibited from possessing such weapons by the Treaty of Sirius. (TAS: "The Slaver Weapon")
The Kzinti phaser was the Starfleet Type 2 phaser artwork colored red. The script specifies that these weapons were, in fact, Starfleet phasers.
In Larry Niven's original short story "The Soft Weapon", upon which the episode was based, the Kzinti were armed with "police stunners" that had just one setting.