Gale Whetstone

Sharpened by the Gale. This whetstone has a total of 1d8+2 uses. You can use an action to use the whetstone on one melee weapon or piece of ammunition that deals Piercing or Slashing damage. For the next minute, the item deals an additional 2d6 Thunder damage when you hit a creature with it. When the weapon or ammunition hits a target, it echoes with a thunderous boom, which can be heard 100ft. away. On a critical hit, the target also must make a Strength saving throw (DC 13). On a failed save, they are knocked Prone. A weapon can only be empowered with this whetstone once per day, and it can be empowered again after the next dawn.