Coated blade

You coat a weapon in a oil type (poison or acid) and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects, and you can cause the oil to leap from the target to a different creature of your choice that you can see within 5 feet of it. The second creature takes oils damage type equal to your spellcasting ability modifier.

This oil’s damage increases when you reach certain levels. At 5th level, the melee attack deals an extra 1d8 poison damage to the target on a hit, and the oil's damage to the second creature increases to 1d8 + your spellcasting ability modifier. Both damage rolls increase by 1d8 at 11th level (2d8 and 2d8) in addition you can choose to make the oil type necrotic and at 17th level (3d8 and 3d8) in addition you can now change the damage type to radiant.