Mistborn, Hero of Ages - The 'snapping' done by the mists reveals mistings. Of these, 1/16th burns Atium. Why 1/16th? There are supposedly 16 Allomantic metals excluding Atium. If you include Atium and Malatium, the number goes up to 18. Should it then not be 1/18th of the affected people (mistings) that can burn Atium? Then, would there not also be a mistborn or two that 'snapped'? Of the 5000 plus in Elend's army that 'snapped', would there not be at least a few mistborn? And would they not stay in bed even longer than the 16 days the Atium mistings (seers) did? Being a mistborn means that they can burn Atium plus all the other Allomantic metals.
I've wondered about this "1/18th vs 1/16th" discrepancy too. I assume that it's one of the author's plot devices, but thought that 1/18 would have made more sense.
Regarding why there were no mistborn within the soldiers that snapped, keep in mind that even among nobles mistborn were rare, as Kelsier noted when he first revealed Vin's mistborn status. Within the trilogy, there were only three known skaa mistborn that Kelsier was aware of - his old master, Kelsier himself, and Vin. Of course, it's possible that there were others, but since noble mistborn were rare, skaa mistborn would be even harder to find.
Kar, one of the Inquisitors, noted that Vin's Allomancy was amazingly strong during the final meeting with Tevidian, the Lord Prelan:
Why, for her to have such strength, she must be of an extremely pure line. At least... one of her parents must have been from a very pure line.
Due to this fact, it's highly likely that the no members of the army had inherited enough Allomantic genes to enable mistborn to be snapped, thereby leaving only newly minted Mistings within the army.
EDIT: In this forum, one of the members recalled a conversation had with the author about this topic:
I asked Brandon about this at his Eagle Eye Books signing during Dragon*Con 2010. (Although you worded it much better than I did at the time.)
Essentially, Brandon said that Preservation wanted the number 16 to be noticeable in a multitude of places. This would make it easier for humanity to realize that something specific / unusual / planned was going on. Brandon didn't say why Preservation chose 16 over 18 (or more, due to other atium alloys), just that Preservation wanted the number 16 to be noticed.
The author also has some notes regarding mistsickness in his annotations for book 3.
On the discrepancy between the known metals and the proportion of mistings in Elend's army
At the end of the original series, We know of the following metals :
- Iron (external)
- Steel (external)
- Tin (internal)
- Pewter (internal)
- Zinc (external)
- Brass (external)
- Copper (internal)
- Bronze (internal)
- Gold (internal)
- Electrum (internal)
- Aluminum (internal)
- Duralumin (internal)
- Larasium (this metal is particular and no larasium mistings would be found)
At this point, Sazed reveals to Spook that there are two metals left. Yet, when looking at other works from Brandon Sanderson, we now know that there are in fact four other metals. It is my theory that Sanderson decided to tweak his magic system a bit.
It is my opinion that, originally, Atium and Malatium were intended to be temporal metals. It all fits the allomantic structure known at the time. Atium and Malatium both let you see other people's shadows/past selves. As such, they would perfectly fit as the external temporal metals. One is also an alloy of the other, another important rule. It can probably also be assumed that one would be a pushing metal and the other a pulling one.
If you decide to classify Atium and Malatium as the missing temporal metals, Sazed is totally right in saying that there are still two metals remaining. Those would be Chromium and Nicrosil, the external enhancement metals that have effects similar to those of Aluminium and Duralumin, except applied to another allomancer (thus justifying the external classification).
This is, in my humble opinion, why there are only 1/16th of Elend's army that could burn Atium, and not 1/18th. This is either an oversight on the part of the author or a simple and forgivable act of retcon.
Sanderson's answers to the question unearthed by JW8 really strikes me as a justification for a retcon by giving another reason for the number 16 to popup, especially since Sazed, at the end of Hero of Ages, explicitely states that there are only two remaining metals to be discovered, not four.
On the reason behind the lack of mistborns in Elend's army
Prior to Rashek giving Larasium to his friends, there were only mistings, and no mistborns. The direct descendants of these original mistborns have a much purer bloodline, augmenting their chances of yielding allomancers.
Through interbreeding, most Skaa have some traces of allomancer blood but it's normally too diluted to be of any use. Only those with nobles as close parents have a bloodline pure enough to allow for snapping and, even then, Skaa mistborns are practically unheard of. And since, in the era described in the original trilogy, nobles seemed to be very careful about half-breed offsprings, it is highly unlikely that Vin or Kelsier's circumstances are shared by many people.
And, as the Asker mentionned, Mistborns in Elend's army would've been among the most afflicted by the snapping. They would probably have been mistaken for Atium mistings, since very few tests were done for lack of time (it was pretty much the end of the world for them).
Regarding the '1/18' question, Brandon has confirmed that Preservation or The Lord Ruler actively changed the magic behind Allomancy, replacing the temporal metals (Cadmium and Bendalloy) with Atium and Malatium (in the Final Empire, the symbols are also used to represent numerals, and Atium and Malatium are in places 10 and 11, cadmium and bendalloy are up at 17 and 18). This meant that there were still only 16 metals, and it also allowed for the creation of atium/malatium mistings, which is where the 1/16th. I dont think it's a retcon either.