I think you should be able to make unarmed attacks against ghosts. After all, you have a soul. There’s a ghost fist inside your flesh fist. You should be able to hit them with that.

If you allow that magic platemail, any magic item should work. Save all your useless and cursed magic items to use in fights as improvised weapons. That also means there’s no a reason people would be keeping cursed weapons for you to find in their loot.