Weapons and armor can only be upgraded via the blacksmith ... The basic materials for upgrading are Copper Ingots and Pine Planks for weapons and Craft Leathers and Jute Garments for armors.

in the game it’s used for more practical things like armor, weapons, and strengthing your flame. It’s not easy to find though ...

For example, Warriors craft better heavy armor using ores like Copper and Iron. Archers use Leather from animals, such as Small Leather or Medium Leather. Magicians and Priests use Cotton or Flax ...