Buzzing Shortsword 2014
Weapon, rare, (requires attunement)
You can use a bonus action to speak this weapon's command word, causing the blade to emit a loud buzzing sound. The buzzing noise is audible out to 100 feet. While the sword is buzzing, it deals an extra 2d6 thunder damage to any target it hits. The buzzing lasts until you use a bonus action to speak the command word again or until you drop or sheathe the weapon.
Properties
Finesse
When making an attack with a finesse weapon, you use your choice of your Strength or Dexterity modifier for the attack and damage rolls. You must use the same modifier for both rolls.
Light
A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.
Source: Vault of Magic (Kobold Press) · License: OPEN GAME LICENSE Version 1.0a details