Eldritch Enchantment

Any simple or martial melee weapon you touch gets cursed with Eldritch Power. You can wield this weapon only if you are proficient in it. If this weapon hits, the target the weapon's base damage plus 1d8 force damage. You can cast this on a free action if you spend a spell slot. Add 1d8 to the damage every spell slot above 1st. 

The spell lasts longer as you level. 2 minutes at 5th level. 3 minutes at 11th level. 4 minutes at 17th level. (Variant rule: level 20-30). 5 minutes at 22nd level. 6 minutes at 28th level.