This marvelous dagger is unnaturally sharp, even capable of cutting through the essence of life itself.  You gain a +3 bonus to attack and damage rolls with this weapon.  In addition, each time you hit a creature CR 19 or less, roll a d100.  On a result of 3 or less, they are instantly killed.

This dagger is a chaotic evil sentient weapon, with an Intelligence of 15, Wisdom of 10, and Charisma of 18.  It's only desire is to kill, and to cause more chaos.

This dagger has 3 charges, and regains 1d3 daily at dawn.  As an action, you can expend 1 charge to cast summon greater demon at 7th level, or expend an amount of additional charges to raise the level of the spell by one per.  The material component is not necessary, but you could provide it for the circle.  The demon summoned is friendly to you, and no concentration is required.  You choose the type of demon.

Proficiency with a dagger allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Melee Attacks, This is based on the daedric artifact from TES V: Skyrim. The original enchantment reads: Has a small chance (1.98%) to instantly kill any opponent (other than Miraak and Karstaag)., creature with a non-lawful alignment, Summoning, Damage, Combat, Sentient, Finesse, Light, Thrown