Shattering Spellstrike

You intentionally channel a rampaging cascade of magic through your weapon, breaking it to deal more damage. Make a Spellstrike against a target with your improvised weapon. If the attack hits, it deals an additional 2d6 force damage as your improvised weapon breaks. If the spell used with the Spellstrike wasn't a cantrip or focus spell, increase this additional damage by the spell's rank.

If the item has a Hardness greater than your level, or if it's an artifact, cursed item, or other item that's difficult to break or destroy, it doesn't break and you don't deal additional damage.