Getting back to "what is hard wax?" M&H tells me it is also known as Jeweler's rouge, a stick of a very hard wax that contains a very fine abrasive such as iron oxide (reddish brown) and is used with a cloth wheel to polish metals (or gelcoat).
It is totally different from softer, protective waxes such as paste wax, Carnuba, etc. and is used as a polishing agent, not for protection.