Tuning Dagger
Dagger (very rare, requires attunement)
A magical musical dagger of explosive properties. When inactive, the blade functions as a normal dagger. When activated (no action required), the blade splits down its middle and separates by a few inches, forming a shape similar to that of a tuning fork. In this state, an attack with the dagger deals no initial damage. However, an attack against an object causes that object to explode in a 10-foot-radius sphere at the start of your next turn. Each creature within range must make a Dexterity saving throw (DC10), taking 4d6 thunder damage on a failed save, or half as much on a success. Magical objects are not destroyed, though the explosion still occurs.
A Bard who attunes to this weapon can substitute the DC with their own spell save DC.
The deadly and musical assassin Scaramouche the Merciless is known to wield this weapon.
Leuku's Balanced Homebrew for DnD 5e 