The fact that you can't access it from the main menu is an unbelievably huge mistake. I mean name one Final Fantasy (older or newer) that doesn't have ease of access to all upgrade systems that are similar to the folio system.
Okay so the stat and weapon skills that you unlock in the folios are the same or different to the ones you automatically unlock with Upgrade Weapons? Different weapons give you different skills to equip and I can’t tell if the folios are part of that or a separate thing idk.