Altheia is the City of the Copper Folk. Its bishops and wise dictators believe that copper is the metal of gods, a holy item given to Altheians as a gift for their religious behavior.
Edit to clarify
The actual reason behind this belief is that in Altheia deaths have been lowered since the implementation of copper in daily life, mostly due to an increase in levels of hygiene as copper kills most bacteria, thus it was seen as an holy miraculous metal gifted from the heavens.
In Altheia everyone dresses in clothing made of copper. The clothes are not too heavy and they are certainly not armor but some small plates are used, not for protection but as decorations and accessories.
The territory of Altheia is so rich in copper that even the streets resemble blue oceans due to their bricks being made out of copper.
But there's one problem: the technology level of Altheia is similar to that of the ancient Greeks during the Roman empire.
How can they make copper clothing, if it's even possible?