Three word monster of "mimic, blade, and parasitic".

A "domesticated" Blade Mimic - a specialized breed of mimic that disguises itself as a weapon for unwary adventurers to find and pick up - chained up at a local adventurer guild for newbie lessons on identifying the difference between mimics and treasures. Unlike larger mimics, Blade Mimics tend to be more of an irritation than actually deadly. Once "equipped", the Blade Mimic latches onto the adventurer's body and drains blood until satisfied. The mimic has little strength and it rarely drains enough blood to kill.

Despite their appearance, Blade Mimics make terrible weapons. They don't have the hardiness or edge of a proper forged weapon and they don't appear to like being used as bludgeon against another beast. There was a fad a while ago of nobles keeping small mimics as pets but that died out quickly as the mimics are extremely clingy at the worst of times and poor people had a good laugh watching well dressed idiots trying to prize off their parasitic pets from themselves.