The dangerous Kemono hunted in Wild Hearts only get stronger throughout the game, requiring players to upgrade their weapons with materials such as Lightstone and Mirrorstone. Unlocked in the early parts of the story, these two materials expand upon the typical improvements players make to their weapons, which only demand parts from Kemono bosses at the start. Both ores are found in the world itself, but players may also find an easy way to farm these materials.

https://screenrant.com/where-to-find-lightstone-mirrorstone-locations-wild-hearts/