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 use a Ripper to repair an auto axe. Also, in V.A.T.S., it will often deal an instant kill.
Outcast gatekeeper ProtectorHenry Casdin at Fort Independence can be seen carrying a Ripper if he has not picked up a better weapon from the occasional random encounter.
There are around 5 Rippers in Andale, in the Smith's basement and in the Wilson's shed. Note that taking them counts as stealing.
Enclave soldiers occasionally carry them and will rush at you with them while some of their squad covers them from afar.
The Ripper does not require an energy source, though it seems to deteriorate quite quickly when in use.
The blade and teeth of the Ripper are covered in blood, suggesting previous use.
It can deal damage quickly and any hostile non-player character's wielding it should be made a priority target in combat, preferably before they can get close enough to use it
The Ripper's appearance is very similar to that of a real-world chainsaw