Yeah I meant if the substance is truly the strongest with no weaknesses. Crystals have a weakness of sheering force in between the cells. If it can be melted, then its weakness is heat. Fantasy materials are often described as being unbreakable, and impervious to heat and chemical reactions. If you can’t shape it, it’s useless. If it requires the heat of a star to melt, or the force of an atomic bomb to bend, then how do you make something useful from it?