Axe of Ymir, the First Weapon

You have a +3 bonus to attack and damage rolls made with this magic weapon.

The Axe of Ymir was the first weapon ever created.  Its blade was carved out of the jaw bone of a long extinct animal and its hilt was crafted out of roughly carved wood wrapped with thin strips of tarnished leather.  Odin, first of the Aesir, used it to slay Ymir, progenitor of the giants.  The axe was lost in the flood of Ymir's blood which coated the world and drown most of the giant race.  It was thought to be lost to history.

Bloody Nightmares - The night following a kill made with this weapon, the user experiences realistic nightmares of being washed away in a flood of nightmares.  If the user is suffering exhaustion, they do not recover one level of exhaustion upon completion of a long rest the same night they have the nightmares.  Additionally, if they are suffering exhaustion, they must roll on the Short Term Madness table found in Chapter 8 of the Dungeon Master's Manual.  They are afflicted with this madness for 1d10 minutes upon waking up.

Supernatural Paranoia - While attuned to this weapon, the user cannot be surprised in combat and is immune to the Disease and Frightened conditions (unless caused by the madness described above).

Return to Dust - The Axe of Ymir deals an extra 2d10 Necrotic Damage on a successful melee or ranged weapon attack made using this weapon. 

Additionally, you can use the axe to cast Disintegrate at the 6th level once per day.  This feature recharges at dawn. 

Giant Slayer - This weapon deals an extra 2d6 Piercing Damage to creatures with the Giant type.  On a successful melee or ranged weapon attack made with this weapon, the giant must make Strength Saving Throw of DC 17.  If the giant fails it immediately falls prone in the space it is occupying.

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

Notes: Bonus: Magic, Favored Enemy: Giants, Damage: Necrotic, Advantage: Initiative, Immunity: Frightened, Immunity: Disease, smearing the milk of a yak along the length of the blade., Damage, Combat, Light, Thrown, Vex