Upgrading is available through the Equipment submenu. It is currently used on weapons to increase the weapon's damage or magic damage.
Upgrading costs a different gathered resource depending on the stat.
You can spend resources to upgrade.
The cost to upgrade Sharpen or Infuse is ((1360(x)+140*(x^2))-(1360(y)+140*(y^2))
The cost to upgrade precision is ((1820(x)+180(x^2))-(1820(y)+180(y^2)).
Note: X=Desired Level. Y=Current Level