Concept: reverse Cursed Shield?

I realize I'm looking like "hey do my work k thanks" but I'm totally lost. I will keep making sprite sheets for you guys so at least there's that, but...yeah

Well before attempting this there's a few things you got to plan. SRAM is the save memory of your game, ranging from RAM address $1600 to $1FFF. There's free bytes there like the japanese swtech name you can change in FF6j. You can check a RAM map for a free spot of 4 continuous bytes.

Second I'd suggest getting familiar with basic coding, a bit like you did with events. This is a good starting point and for details on each opcodes, you can check this page. No need to read completely the second document, though I'd recommend it eventually. I learned coding by trying to understand simple commented operations in the disassemblies, then I tried simple stuff on my own. When I was hitting a brick wall, I was using the debugger. To simplify your life, I suggest also you start right away with an assembler like xkas instead of sticking to hex editing for ASM. You will limit your hex typos and the fact of rewriting more bytes that you need everytime you do a little tweak.

You should check the end of battle code in C2 (which is pretty long) where you receive gold and magic point. There's no specific place wehre you need to put the code, but you can't put it anywhere at the same time. The disassemblies are a gold mine of ASM examples since there are commented.

If you have specific questions, feel free to ask though I don't have time to do your request completely. I'll learn a lot more if you at least attempt it yourself.