In the Shadows of the Last War
When you attack an object with this magic sword and hit, maximize your weapon damage dice against the target.
When you attack a creature with this weapon and roll a 20 on the attack roll, that target takes an extra 14 slashing damage. Then roll another d20. If you roll a 20, you lop off one of the target’s limbs, with the effect of such loss determined by the DM. If the creature has no limb to sever, you lop off a portion of its body instead.
In addition, you can speak the sword’s command word “Tekaan” (shine) to cause the blade to shed bright light in a 10-foot radius and dim light for an additional 10 feet. Speaking the command word again or sheathing the sword puts out the light.