It is rarely found outside of Enclave populated areas at one time or another. Rare compared to other melee weapons in Fallout 3, the Ripper is unique in that the player can hold down the attack button and an enemy at melee range will continuously receive damage. The Pitt, however, adds a weapon with identical functionality, the Auto-Axe.
You can also use a Ripper to repair an Auto-Axe. In V.A.T.S, it will often deal an instant kill or inflict serious damage depending on the value of the melee weapons skill.