Wordweaver

Wouldn't it be impossible for inquisitors to "see" aluminum? They rely on metal sight, which, conveniently enough, means that anything made of aluminum should be completely invisible to them. Getting it in large quantities would be an issue, but with alloys and such, you could probably stretch a bar or two enough to make a deceptively harmless weapon.

I'm not saying that gold should make you younger in and of itself. Brandon has said numerous times (both in-character and externally) that it doesn't work that way. But, since it is effectively restoring you to what your soul says is a "natural" state, it should theoretically restore your natural age, too- whether you've been storing 20 years in a metalmind, or you're a thousand years older than you have any right to be. It obviously doesn't work that way, as shown by TLR. I guess that means it's either an oversight, or there's yet another factor which prevents it from working on age.

This seems to indicate that storing large amounts of age nets you some "free" longevity, as your soul attempts to revert the physical aging. I wonder whether you could re-invest the resulting youth. It would be an incredibly inefficient system, to be sure, but with a long enough lifespan... Also, if feruchemical gold uses your soul as a blueprint, shouldn't it reverse the effects of atium feruchemy?

If we go the "survivalist" route with exposure endurance, it might be neat if it came with temporary muscle memory and survival instinct. Not much, mind you. It's still a physical metal. In terms of mythic hemalurgy, would you make the qualities unknown for the sake of mystery, or due to a lack of ideas? If it's the latter, I'm sure we could help you out. Age/youth is good, although it might be slightly more self-explanatory if we called it longevity.

Exposure endurance and body control both sound neat. Sensory resistance and blood quickening seem a bit too specific, though. I can't imagine their being particularly useful outside of a select few situations. Metal incorporation is interesting, but I would almost say it fits hemalurgy more than it does allomancy. It's hard to tell- I'm not sure becoming a literal iron man fits with any of what we've seen from the metallic arts. It's definitely a fun idea, though. It would be neat if we could make that work. Speaking of which, mythic hemalurgy might be interesting. Stealing powers is (painfully) obvious, but we could determine what mundane attributes would be taken via spikes. Maybe we could even come up with some hemalurgic constructs?

How about persuasiveness? While storing, people would be inclined to argue with everything you say, but while tapping, people would be inclined to believe you. A compounder could convince someone of almost anything. It would need limits, of course. I would probably draw the line at persuading someone of something irrational, opposed to their current beliefs, or simply ridiculous. It would be interesting to make the line a little "wavy," though. Giving well-constructed arguments* the ability to bend the rules might lend itself to subtlety and clever manipulation, rather than the brute-force approach which tends to be ore common in Feruchemy. *The arguments in question would likely involve logic chains, flawed logic, and points that seem reasonable on the surface. Those would most likely be easy or boring- Feruchemy will make them effective. The more interesting part would be stringing them together in such a way as to take advantage of a logical progression, built-up opinions, or existing beliefs.

Since we're making metal sight a distinct power, it's probably best to avoid sticking it to anything that doesn't absolutely need it to function. Otherwise, you get a two-powers-in-one type of thing, which really shouldn't be happening. That said, metal sight, as it is, is basically just a very limited form of x-ray vision. Those bells and whistles would probably serve to make it somewhat more interesting and useful. Just for the sake of throwing more ideas on the pile: Strengthen metal, which makes metallic objects hard and inflexible. This would probably have the additional property of making liquid metal temporarily solid. This would probably burn slowly, and would be handy for things like keeping your weapon in one piece or turning a piece of tinfoil into a makeshift shield. Liquefy metal, which temporarily melts solid pieces of metal. There's no heat involved, so you can theoretically use it to swim in a big block of metal. That said, it would burn rather quickly, so using a piece of steel as your personal swimming pool isn't a great idea. Great for destroying metal objects, using large objects to refill your reserves, or walking straight through a metal cage. Accelerate metal, which, as the name suggests, speeds the movement of metal objects. To make things more interesting, and to help differentiate it from iron and steel, this would probably effect all metal in the user's vicinity, in the same way as a bendalloy or cadmium bubble. Note that this affects gravity, as well. Good for making bullets more destructive, throwing makeshift weapons, or making falling objects deadly. A very adept savant could probably use metal powder to tear things (or even people?) apart. Slow metal, which is the opposite of accelerate metal. It will slow the movement of all metal in the user's vicinity. Flared, it can stop movement (including downwards movement due to gravity) completely. Good for making temporary platforms, rendering weapons useless, using metal dust as a shield, delaying the collapse of metal structures, or stopping bullets. Used creatively, I suppose it could also be an interesting way to pickpocket. I imagine that mistings who can accelerate or slow metal would carry an assortment of metal objects. Coins, metal powder, and tinfoil are probably the most obvious, but metal plates inside shoes or gloves would have several interesting applications. Durability might work as an internal physical metal. It would simply "harden" your body, possibly at the cost of speed and flexibility.

Aura abilities have the potential to be overpowered, but there are lots of ways to balance them. In normal Allomancy, there are three "aura" metals- copper, cadmium, and bendalloy. They're balanced largely because they have firm, definite limits, not to mention the occasional drawback. Bendalloy and cadmium bubbles both restrict interaction with the outside world, and copper is practically useless in and of itself. Something that's been done a little less in normal Allomancy and Feruchemy are abilities that have the potential to be double-edged swords. If we did it right, an aura effect would probably be very conducive to that sort of thing.