damien

After Harmony said that Wax could now burn Pewter I had assumed that the first vials had included Steel, Pewter, and Lerasium alloyed with Pewter to make him a pewter misting also. It is known that a misting can be created by combining Lerasium with the metal the misting would be able to burn. I see no reason a person can not be granted to be a multiple misting, it just probably never happened before because why do that if you have Lerasium and can be a full mistborn. But in this case Harmony did not want the existence of Lerasium to be known. So he secretly granted Wax the ability to burn pewter which he probably did subconsciously similar to Vin before she knew what she was doing. This would just help give him the power to keep going during this mission.