Ah...too bad, but a fun thought to think about-thanks for the answer
I was also thinking that, in Dominions 4, it would be nice to be able to individually assign slots to units, like one would make a new unit. You could, for instance, create a new slot "right wing" or "wings" for a mod, assign it to a unit, and then create a forged item that would go on that slot.
Protection could then be a function of the number of total slots, divided or reduced somehow in comparison to the total size of the unit, in relation to how much of the total unit was protected, with "no slots" defaulting to natural protection.