Hi guys, happy new year!
I just read Chapter 3 of BOM. It disclosed the possible usage of nicrosil and aluminum in feruchemy. I believe this could be some hints on how southern people used metallurgic arts.
BS once mentioned:
It confused me quite a while until BOM Chapter 3. I believe nicrosil-mind is the key.
Here is my speculation:
Nicrosil could be used to store investiture, which includes any allomancy or feruchemy power. If someone is a F-nicrosil+A-bronze twinborn, he can store his seeker ability and tap in a short time to achieve extraordinary strong seeking power. With this power, he can easily pierce copperclod just like what Vin did under the charge of her hemalurgy earring.
Thank to aluminum and Trueself, now we have some way to make use of some others' metalmind. That means, someone who is not a metalborn could achieve some allomancy or feruchemy power temporarily by wearing a generic nicrosil-mind.
Productivity of nicrosil-minds seems to be a problem? Don't forget, we have compounding! With compounding, we can gain much more allomancy or feruchemy power than we stored. As long as we have enough nicrosil to support compouding, we can create many-many nicrosil-minds to support a full-born army.
Nowe we can speculate what Rashed did to help people surive in the south. After his accession, Rashek must leave them a set of nicrosil minds which included most allomancy and feruchemy powers and told them the knowledge to use them. With those nicrosil-mind as "the first pot of gold", southern people should be able to mass product allomancy or feruchemy.
For southern people, allomancy and feruchemy may not be a inherent gift, but the power from their nicrosil-mind equipments. However, although Rashek may leave them some nicrosil and alumnium to support the production at the the beginning, those could not be much. Nicrosil should be the most important resource in the south, as how much nicrosil they have, how many full-born warriors they can create.