Blade Beam

Touch a melee weapon and until the weapon is dropped or the spell is dispelled, a wave of energy will be launched from it when it is swung. Make a ranged spell attack against the target and upon hit the spell will do 1d6 + 2 force damage from any range up to 15 feet, after which it does half damage for an additional 10 ft (25 ft for those who are mathically challenged) before dispelling in the air. 

Does an additional d6 of damage for every 2 spell slot levels higher.