This weapon is made from a meteorite that fell from the heavens centuries ago.. and has been used for villainy ever since it was first created... well not so much created as found...

Its a magic rock.

The wielder of the magic rock gains Throw Rocks (Strength 8). The rock can also be used as a missile weapon, also at Strength 8, and will return to the wielder after each throw. The rock increases the wielder's attacks to Strength 8 in hand to hand.

Not only that, depending on the adventure.. you could customise the rock (!!!) For low level characters (1 maybe 2) make the rock Strength 6 if there are a number of other monsters with the badguy.

For midlevel characters(4-5), its a better thing for the big badguy's bodyguard.. (a sorcerer with a huge ogre) and the rock can be Strength 10. Higher level characters are tough enough that the badguys will have even better weapons... no rocks for them...