Looks like it's because this was missing from Piratez.rul
- name: MEGASCORPION_ARMOR
needItem: true
destroyItem: true
I first "fixed" by removing MEGASCORPION_ARMOR from Piratez_Events.rul but I think this tweak actually fixes the problem without removing the event. So now I have no idea what the event actually gives you but it happened pretty early in that game.