Arondight, Unfading Light of the Lake

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

 The sword of a noble knight, it was forged in the realm of the fey and gifted to this knight to prove his status as the greatest among his comrades. This sword grants its wielder advantage on all Strength rolls while in combat. In addition the wielder is immune to being blinded while attuned to Arondight. Arondight grants the power of the fey on its wielder, giving them proficiency with the item regardless of class. 

Arondight has 4 charges. 

Overloaded Light. As an action, you swing Arondight and expend a charge, it releases a flare of bright light, the attack deals 3d8 radiant damage and 2d8 slashing damage to the target. Additionally, the target must succeed on a Constitution saving throw or be blinded. A creature blinded by this ability makes another Constitution saving throw at the end of each of its turns. On a successful save, it is no longer blinded. Arondight regains 1 charge each day at dawn. 

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

Notes: Advantage: Strength Ability Checks, Blinded, creature of lawful alignment, Versatile, Sap