How to make the copper set more unique

I feel copper tools/ armor should be more of an iron counterpart to choose from rather than more filler in early game, I think the way to do this is make the copper items oxidize as they lose durability for each quarter of the items overall durability. Every stage the item increases efficiency, at first the items resemble the speed/protection of stone/ chain mail, after the first 25% it improves to iron speed/ protection, then diamond, then the speed evolved to the speed of gold. This would make the copper set stand out more, but be a choice if people prefer it.