What is Nerfbat?
1.
A term used when something in a game (generally an MMOG or FPS) is weakened considerably.
Nerfbat came about because Nerf creates harmless versions of harmful devices (swords, guns, etc).
When an MMORPG developer gives something the nerfbat, they often drastically reduce the effectiveness of said item.
see also:
SOE has given the Sword of Demon Slaying the nerfbat; it can barely pommel a rabbit to death in its current state! - nerfbat