Okay, cognitive metals. This is where things get really difficult for me. These four powers are all super high on my list; I think they're all incredible.
Brass (Warmth): This one used to be my pick for being a ferring. Never being too cold or too hot? Yes please. The obvious draw to this power is it being equally useful for both storing and tapping. Winter's chill doesn't get to you. Summer's heat is a pushover.
What I realized about this power, though, is I'm not often bothered enough by being too warm or too cold to warrant me picking it. Especially where I currently live, I survive both the coldest winter nights and hottest summer days relatively well. Obviously it's not a fun time. But it's not that much of a bother. If I lived in a place where the temperature varied more and I couldn't really deal with the heat or cold, this power would be more attractive. Currently, though, I'm not all too interested.
I know I did say I think all four of these powers are incredible, but I did just tear on Brass a little bit. Probably too much. I still think the power is super cool. There are also minor applications that would be fun to experiment with. Tapping tons and tons of it to potentially light things on fire around you. Or tapping a lot to warm people near you up.
And, as I said earlier, this used to be my top pick. It's still high up there for me, I think. I've just realized that I live very easily without controlling my temperature through said means.
Verdict: Still awesome, but I live just fine in my day to day life just dealing with the differing temperatures.
Bronze (Wakefulness): I really really like this power. I think it's important to make sure you get the full effectiveness out of storing it. On paper, storing it doesn't seem that useful; you just spend an extra hour asleep and then later you could tap it for an hour. So, in the course of a day if you did that, you would wake up an hour later and stay up an hour earlier.
But. But.
There are a few ways to make storing it awesome. First off, it becomes super easy to fall asleep anytime, anyplace. And. And. You can stay asleep for as long as you want. During car or plane trips, it's effectively time travel into the future. You just get to be at your destination (supposing you're not driving). You're just automatically there.
Also, I think it would be surprising how in random scenarios in life you could store it for just a few minutes. I forgot my book at work or am waiting for a new book to come, I can just store wakefulness during my break instead of wasting time looking at my phone.
Tapping it has its clear uses.
Maybe I'm overrating this power, but I think it's super cool.
Verdict: Super awesome (imo)
Zinc (Mental Speed): In Bands of Mourning it briefly takes about how tapping mental speed makes you hungry. So, presumably, storing it would allow you to not be hungry? That's not that important, especially since we don't really know how it works, but I thought I would mention it. It also probably gives signs of what's actually happening when you use the power.
Anyway. So, one misconception I had a few years back about this power. It doesn't increase your intelligence at all. It just allows you to think more in a given amount of time. Effectively, time stopping to allow your brain to think.
Storing it would suck. Sazed talks about how he has to struggle to comprehend every word said etc. But, storing it does have its uses. Theoretically, you could time jump with this power, similar to how someone would time jump with storing wakefulness. You store so much mental speed that it just seems like time is passing super quickly since you can't process anything or something like that. The benefits of that have already been talked about.
How useful is tapping it, then. I'm not exactly sure. I wouldn't use it during tests because I feel like that's cheating. I could read faster with it. That'd be nice. If a lot of things are happening around me at the same time, I could easily process and understand all of it. I could listen to several conversations at once since I would have a lot of time to think about what the people are saying. At work when we're particularly busy, it would be nice to be able to process everything that's happening easier.
I think a weird tiny benefit that we might not think of is being able to "live in a moment for longer", if that makes any sense. If there's something exceptional going on, you could have it, effectively, go on for a longer period of time. I'm not sure how often I would use the power like that, but I do think it's cool.
I think one thing that makes this power cool is thinking about the potential of it. If there's a really hard question or problem or something, you can spend a lotta lotta time and solve it in what seems like an instant to other people. It's cool.
Verdict: I think it's cool, but I'm not quite sure when I need to think more at any specific time.
Copper (Memories): Here's the thing about Copper. 1. It's awesome. But 2. I kind of want to keep the memories. Memories that I want to be able to get a fresh copy of at any time would be memories I wouldn't be willing to store in the first place. So, the memories I would store would be ones that I could have multiple copies of. I would make an additional copy in my Coppermind so at any time when I really want the info/watch/see the thing, I could.
One weird thing about this. We learn in the annotations for the Mistborn Trilogy that Sazed was trained at a very early age to memorize very very very well. He has crazy crazy good memory without ever touching a Coppermind. So, the question is, how well would memories stay put in my brain? Sazed is able to take and put back information into his Coppermind (I don't know why I keep capitalizing it, but I am) many many times without needing to replace the old copy with a new one. How many times would I be able to take information out, then put back in, without needing to refresh them? I'm predicting it would be far far less. Which obviously isn't a good thing.
I wouldn't use the power during tests because I feel like I would be cheating.
Even with all this said, I'm sure the power would be incredibly useful and super awesome to have. It pretty much eliminates small written down lists. In many forms at least.
When there's a random phrase or idea that you want to right down, but you can't because whatever reason, you can just chuck it into a metalmind.
You're getting rid of the specific words or whatever in your head at that moment, but you'll remember the build up to them, so you'll still have that memory of them. Point being, you have both your actually memory and the memory in the Coppermind.
Things like visual memories or audio memories for things you can only see/listen to once are the memories I was referring to at the very beginning of this portion. I'd rather have the actual memory of them rather than forgetting them just to remember them later. I want them to be a part of me, not whisked away.
Although you would still remember how you felt and such if you did put the memory away, which is weird. Copper is weird.
Longer memories would be a thing you could store parts of. You're watching a really pretty sunset/sunrise? Those last a while, so you could store parts of the memories, so another time if you really want to see the sunset/sunrise, you totally could.
Verdict: Copper is wild and incredible. Also very very fun to talk about. Also I want to talk more about Bands of Mourning stuff because I just came up with new theories on stuff and I want to spread my ideas. That was mostly irrelevant to this verdict, but whatever.
Rankings:
4. Zinc.
3. Brass.
2/1. Copper/Bronze. Still not sure on this one.
(I'm not rereading this right now because it's a lot, but I might later and edit a few things)