6 points
I believe bronze and iron weapons are equally powerful, but bronze is a mixture of copper and tin (requiring two types of input). Iron is more plentiful than tin, so militaries do not need large supplies of tin if they can manipulate iron. Steel, I believe, needs much higher temperatures and purified inputs.
8 points
4 points
-13 points
20 points
8 points
-6 points
2 points