Unearthed Arcana
1-level Transmutation
You channel arcane energy into one simple or martial weapon you're holding and choose one damage type: acid, cold, fire, lighting, poison, or thunder. Until the spells ends, you deal an extra 1d6 damage of the chosen type to any target you hit with the weapon. If the weapon isn't magical, it becomes a magic weapon for the spell's duration.
As a bonus action, you can change the damage type, choosing from the options above.