Abyssal Blade

Weapon (greatsword), rare (requires attunement) You gain a +1 bonus to attack and damage rolls made with this magic sword. This sword can pierce a creature down to its soul. When you hit a creature with this weapon, as a bonus action, you can force that creature to make a DC 16 Constitution saving throw. On a failed save, that creature is stunned until the end of your next turn. The sword can't be used this way again until the next dawn. The lost blade of the Commander of the Abyss, this edge cuts into an enemy's soul.