Era 2 Leather-bound Hardcovers

[The Isochronism he/him]

So something has been driving me crazy lately, and I don't see a topic for this. What is the allomantic metal on the Shadows of Self leather-bound. I can't find it on the chart, yet I KNOW I've seen it before and it will bother me forever if someone doesn't tell me. I know that the Final Empire leather-bound has Iron (assumedly because it's the metal Vin uses to pull the bands of mourning out of the Lord Ruler's arm) The Well of Ascension leather-bound has Steel, (Probably the most used metal, don't need a reason for this.) And the hero of Ages leather-bound has Tin on the cover. (Cause spook obviously.) But then the Alloy of Law has Pewter, which doesn't make a ton of sense given that there's only like one pewterarm in that book and I don't even remember his name, and I don't recognize the symbol on Shadows of Self leather-bound. So please, help me out here.

Also let me be the first to say, the Mistborn leather-bounds, especially the new ones, are gorgeous. Possibly the most beautiful creations known to man. I am so happy I was able to get a signed and numbered one, and I am so exited to get that. 

[Pagerunner he/him]

They're just going in numerical order down the Steel alphabet, so #5 is Alloy-era zinc. https://coppermind.net/wiki/Steel_alphabet

I think any thematic ties to the content of the books are purely coincidental.

[The Isochronism he/him]

Hm, how sad. Interesting how some of the symbols changed across eras, that's why I didn't recognize the SoS leather-bound. Awesome stuff though.