The Ravager Droid was desinged by K471 for the purpose of elimination of his enemies. They droids were incredibly fast, and their bodies were designed to be weapons in upon themselves. Though they were armed with four built in blasters (one on each arm and one auto-targeting weapon on each shoulder), they were designed for close combat.
Once these droids passed into the enemy ranks, they could decimate living beings with precision and ease. Only one droid was considered a viable threat to most enemies, while a whole group was a sign of defeat. The Ravager was an incredible advancement in droid soldiers.
Many of these droids were put to the test during the Sith-Cylon War, where it was found that the program had a potential flaw in dealing with Jedi and large groups with focused firepower. Cylon Cybernetics was instructed to work out these flaws, and upgrade the droids to the next level. This design flaw has yet to be corrected.