Some spoils seized from monsters and treasure chests contain rusted pieces of equipment. While seemingly useless in their rusted state, these items can be taken to a polisher who will restore them to their original power.
Alchemy
Certain items can be endowed with new powers if you bring them to the alchemist in a town or village.
Create and Modify Weapons
You can forge new weapons and protective gear, using materials like scrap iron and Ether Stone at the blacksmith's shop. The blacksmith can also improve existing weapons and gear by adding new materials to them.