You can ENHANCE a GEAR by clicking on it.
By clicking FORGE, you can access the needed materials to enhance it.
A GEAR can be forged up to +10 if you have ENOUGH materials.
When your GEAR reaches +10, you can AUGMENT it by adding another star, unlocking another effect, and renaming it (this will make your GEAR stronger).
It is possible to AUGMENT a GEAR up to +10. You must SCRAP duplicate GEARS in order to obtain the materials you need to fabricate or augment your gear if you do not have ENOUGH.