Actually it was all you with the breakpoint Chillyfeez! Without that starting point I still would have had no idea how to approach the issue.
That is almost definitely how it would work Pinkpuff. The way of having a single subtract byte instead of an index saves a lot of space. But it may be with equipment that there's a single byte in all of that, hopefully that won't be the case and each equipment section will have its own -byte.
I was looking for how Items find events, but most of my research came up blank. I thought I could use a similar method to how I found the Summon Items, but I may have to go in a different direction with that.