Eldritch Weapon

One simple or martial weapon you’re holding becomes a magic weapon until the spell ends if it isn't already magical. Choose one damage type: thunder, poison, lightning, fire, cold, or acid. You deal an extra 1d6 damage of the chosen type to any target you hit with the weapon for the duration. You can change the damage type as a bonus action, choosing from acid, cold, fire, lightning, poison, or thunder.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the spell's duration becomes concentration, 8 hours.