Motorized bladed implement, used for logging and lumberjackery-related activity. 

Is terrible (as in ineffective) as a weapon, due to being unbalanced and the chains snagging horrifically on flesh and bone. This doesn't stop fiction from turning it into the metal-er modern day melee weapon of choice.

Doomguy likes to call his "the Great Communicator". Doomguy is nothing if not talkative, after all.