Hoarfrost Blade

You gain a +2 bonus to your attack and damage rolls made with this magic weapon, and the first time you hit a creature on a turn you deal 1d8 additional Cold damage. When you target an Aberration or a Fiend with a melee weapon attack with this magic weapon, you have advantage on the attack roll.

Sap (Mastery): If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.

Versatile: A Versatile weapon can be used with one or two hands. A damage value in parentheses appears with the property. The weapon deals that damage when used with two hands to make a melee attack.

Proficiency: martial, longsword Source: Treasures from Oerth p. 17 (Homebrew)