Board Thread:The Last Sovereign Discussion/@comment-27713488-20180327004110/@comment-35006067-20180506140337

The fact that we can find a Shining Sword just lying around in a chest in the Holy Dimension + Carina's comment that it belongs here + Robin and Carina cooperating to repair the "holy mirror" in the same dimension a little bit later, could be foreshadowing for Carina and Robin crafting things together using the Shining Swords.

Though, from a gameplay perspective, I don't see it happening before Chapter 5.