Actually, I think the disagreement is as follow:
Side 1: If a wooden chain shirt can exist independently of the darkwood special material, then what we are doing is applying the darkwood properties with the base item being a wooden chain shirt. So, when we read those sentences, we evaluate normalcy in terms of the base item, a wooden chain shirt. A wooden chain shirt is, by definition, normally made of wood.
Side 2: Even if a wooden chain shirt can exist independently of the darkwood special material, what we are doing is still applying the darkwood properties with the base item being a chain shirt, without qualification.