Weapon (Glaive, Greatsword, Longsword, or Scimitar), Very Rare (Requires Attunement)
When you attack an object with this magic weapon and hit, maximize your weapon damage dice against the target.
When you attack a creature with this weapon and roll a 20 on the d20 for the attack roll, that target takes an extra 14 Slashing damage and gains 1 Exhaustion level.
Source: SRD 5.2.1 · CC-BY-4.0