Dread Blade

Imbues any non-magical, bladed melee weapon held by the caster with dark magic. The weapon is enveloped in darkness and gives off a faint black mist. On attack, the imbued weapon deals a bonus of whatever damage type the target is weakest to. If the target has no weaknesses, the weapon deals slash damage. When the imbuement's duration is reached the weapon reverts to it's original form. This spell can be cast again after a short or long rest. The imbuements strength grows with the caster's level, dealing 1d6 damage (as well as the weapon's base damage) at level 1, as well as an extra 1d6 at levels 10 and 20, resulting in a maximum bonus of 3d6 damage at character level 20. If the imbued weapon fails to connect with something when swung, a sweeping slash of dark energy is sent in the direction of the swing, traveling at 20 feet per second and dissipating upon reaching 10 feet or hitting something. Slash attack deals 1d4 of slash damage at character level 1 and an additional 1d4 at character levels 8 and 16, resulting in a total of 3d4 at character level 16.