Astral Chain is rather interesting in that you pretty much keep the same weapon the entire game. Instead of switching it out, you can upgrade it and select different forms. The upgrading part comes a few Files into the game, but it can be very useful to do once you are able to do so. This guide will explain where and how you can upgrade your weapons.
Unlike some of the other major areas found in Neuron HQ, the area to upgrade is not included in the fast travel list once you obtain it. Instead, you must fast travel to the Training Room and then walk down the hall and enter the door that is known as Training Crew.
Once in this room, go to the right and speak with Tabitha to bring up a menu, where you should then select Upgrade. At this point, you can select between your X-Baton and Legatus to upgrade. You can see on the right side what the next upgrade would add to either of them stat wise.
To do these upgrades, you will need a few different things. The first of these is just money, which increases quite a bit the more you upgrade them. In addition, you’ll also need varying types of Material Codes, which also go up the higher level your X-Baton and Legatus become.
With the cost of these being so high, you may want to look at our guide on how to recycle in the game to earn some extra money to use here as well.