The Elder Scrolls: Tamriel real

This magic sword maximizes damage dice when you hit an object. When you roll a 20 on an attack against a creature, it takes an extra 4d6 slashing damage. Then roll another d20—on a second 20, you sever a limb (or a body part, per GM discretion). You can speak a command word to make the blade shed bright light in a 10-ft. radius and dim light for another 10 ft. Speaking the word again or sheathing the sword extinguishes the light.