Steps to reproduce: I have downloaded the Shadow Dragon Nightmare modules, and I am able to open the decompressed database file in Nightmare. I can load the Nightmare modules for class, character, and item editing.
Is there any way to add new items to the game? I understand how to edit existing items, but is there any way to add completely new ones with custom stats?
Disclaimer: I have never hacked fe11, so take my advice with a grain of salt.
Generally speaking you’d need to repoint the item table into free space eg. replace all pointers to it with the new address. I think nightmare to csv possibly works for non-gba games, which would do this stuff for you.