The only ship to ever carry this weapon
A Graviton Cannon is the smallest gravity-based starship weapon. This device is basically a souped-up tractor beam emitter. It fires a pulsed series of gravitons to produce a rapidly oscillating gravitic field. As the beam passes through an enemy starship, parts of the target simultaneously feel powerful gravity fields in opposite directions only a few meters apart, and the ship is literally torn apart by its own weight.
This system was only ever installed on the EFS Stornoway, an experimental modification to a Rota-Class destroyer design. Although initial tests carried out by Erich Von Shrakenberg were quite promising, the greater cost in terms of money and maintenance compared to quite-adequate weapons such as Lance Torpedoes led to the termination of the project.
Behind the Scenes
This weapon system is based on one Martin Hohner created for a never-completed Star Trek fanfic story he tried to write back in High School.