I would assume the stern lanterns were made of copper or brass to prevent sea salt corrosion.
Are you scratch building them on your model ? Have a look at Shapeways stern lanterns for Victory, they are excellent.
Pictures seem that the base was wood, the top was metal
I asked the information on the victory, but it's intended for the Santisima Trinidad, I needed to decide if I was going to rust or do paint chipping effects, ended up deciding on rust anyway