Thank you, @Honorless! Lost causes have never daunted me before, no matter how much experience I have gained telling me that they should!
Nicrosil compounding?
Perhaps, but it's been hinted (can't find the WoBs right now, but they're out there) that there's some sort of inverse-Compounding. It's never sounded like that would be Nicrosil, (given how reticent Brandon has been) but I could be wrong.
They store determination.
Yeah, but have you ever thought about how weird that is? On the Feruchemical table, Electrum is a "hybrid" metal, and the other three in that category are Gold, Cadmium, and Bendalloy, which store health, breath, and nutrition/calories respectively, none of which are anything like determination, and in fact are very physical. In the Cognitive section of the table, we find Copper, which, storing memories, rather nebulous things, is probably the most comparable to Electrum, but it's still wildly different. Copper stores definite memories, and memories have, at least in the sense of, well, sense itself, a coherent identity, they're a thing that exists. (Copper is really weird as a Feruchemical metal as well, seeing as how it stores actual pseudo-objects rather than qualities, but that's a different story) Determination, though? Is it an emotion? A neurochemical hormone? What, exactly does it mean to be less determined? The Arcanum descriptions make it sound a tiny bit like being controllably bipolar, but that isn't really what "determination" means. It's not a Spiritual attribute, which are the second most comparable, but everything we've heard makes F-Electrum sound a lot like the Feruchemy for dealing with Spiritual attributes. The non-Spiritual metals are rather definitive. Store wakefulness and you go to sleep. Store health and you get sick. Store breath and you start hyperventilating, etc. The Spiritual metals? Store Connection and you get... less... Connected. Your friends don't like you as much or something? Huh? (Is this why Jak is always so... mildly callous towards Handerwym? The "I am proud to count a savage as my friend" incident, was Handerwym storing then? Hmmmm...) Store Identity and you're... what? Who knows? Not you, because there isn't a you, kind of! Not really! Someone help! Store Fortune and you're... unlucky? How does that work? If you lie in bed and do nothing that could involve the vagaries of chance, but start storing as much Fortune as you can, are you going to have an aneurysm? Store Investiture, and you're... less invested. What the heck does that mean for a Nicrosil Ferring? Shouldn't storing Nicrosil Investiture make one less able to do that storing in the first place? The pattern continues with determination. When you store in an electrummind (okay, that word should never be used again), you're... less... determined. Is that just motivation? Do you not feel like doing things as much? How much can you store? Is it purely a mental thing, would the maximum storage be suicidal tendencies or something? Or is it something deeper? Could you store enough determination to make your subconscious just give up and stop running basic body functions? That'd be a bit dangerous. What if you were already storing just a little too much determination, became suicidal, and then just stored all the rest? That'd be a neat party trick. (Is this why we haven't seen any Pinnacles yet?) The same with tapping determination. You become.. MORE determined! Huzzah! You're... what? How does this work? Do you become motivated enough to do everything you think of doing? This sounds like it could be a bad thing. It also sounds like getting drunk. Is it really a lowering of inhibitions? Or are you just more motivated to get things done? Is it a good thing or a bad thing to tap determination?
TL;DR? I think determination is either really really weird or a Spiritual attribute. Leaning towards the former, but that doesn't help much. I really hope we see a Pinnacle as a main character in some books soon.
Ah, I hadn't seen that WoB. Everything I had seen seemed to specify that Zinc was only mental speed, but I guess I was wrong. On that note, can Zinc Compounders create the Diagram? Without becoming psychopaths?