A Good Excuse to Backtrack
Hopefully you picked up the chest key on the floor by the entrance of Gathelatio's Sanctum. Having waited for so long to acquire the key to open the blue locked chests, we bet you've probably forgotten where they all are. Unless you kept a note of their locations like we did, of course!
Actually, despite the long wait, most of the chest contents are actually merely "nice", rather than "wow, amazing!" and very quickly surpassed by other equipment you'll soon acquire. That said, you should definitely grab the humanoid-slaying weapons if you have time.
In addition, you'll probably end up trekking all across Luxendarc anyway, if you're looking to obtain the job asterisks that you missed during your first run. So you can kill two birds in one stone by looting the blue chests while you're there! Not all chests align perfectly with this route though.
|Central Command - 48F||Longinus (spear)||-|
|Harena Ruins - B2||Yoichi's Bow||-|
|Ba'al Crater - Descent||Hadean Claws (knuckles)||Deals dark damage|
|Miasma Woods - Centre||Heiji's Jitte (rod)||Use to trigger Takeover|
|Harena Sea Caves - Centre||Air Knife (dagger)||Deals wind damage|
|Grand Mill Works - 2F||Fortuna (firearm)||Chance of instant death|
|Mythril Mines - B2||Blessed Shield||Use to trigger Cura|
|Geyser Grotto - Centre||Doujigiri-Yasutsuna (katana)||Effective versus humanoid|
|Starkfort - 3F||Kokusenpu (axe)||-|
|Witherwood - Interior||Musashi's Oar (staff)||-|
|Engine Room - B28||Kokusenpu (axe)||-|
|Everlast Tower - 3F||Ripper (dagger)||Effective versus humanoid|