I like your post, Phaz but I also disagree with some of it.
So, Inquisitors. We know that they can be made from allomancers (Marsh). We know that they have the powers of a mistborn. We know that their abilities are usually stronger than normal Mistborn. We know that they use allomancy.
We do not actually know that they have the powers of a mistborn, at least from what I recall. If you have a passage to support this, I would appreciate it. As is, we know that they can push/pull metals and that they can use atium. It is likely that they strengthen themselves with pewter. However, I can't recall an inquisitor ever using emotional allomancy. They would have no need of tin as it would not help their "blue line" vision anyway, and hearing better wouldn't really help them. They don't need aluminum, and likely not duralumin as they are so powerful in the first place. I would say that it is possible that they have the powers of mistborn, but has by no means been proven.
The other debate is whether or not they use allomancy. I would think that some of them would be mistings and thus could use allomancy. However, we have yet to see an Inquisitor actually ingest metals. They could possibly be allomancy/hemalurgy mixture users, but there is just as much evidence to suggest this as there is that they are pure hemalurgists.
The reason the two systems are so incredibly similar is because, quite simply, I couldn't think of anything at all for hemalurgy to give them. We just haven't seen much of the inquisitors. I personally think that they are too similar as well. I think that they would naturally have similarities, as well as with feruchemy, but I couldn't think of what other powers to give the inquisitors.
I don't see a reason to have two magic systems that have the same powers, just different sources of that power.
Neither could I, but then I noticed something...
In Allomancy, Pewter supplies the burner with added strength and speed. In Feruchemy, Pewter stores strength and steel stores speed.
In Allomancy, tin increases the users senses. Tin allows a Feruchemist to store senses.
Allomancers use atium to see the future, but it also speeds up their thought process. Feruchemists can accomplish this thought speeding with zinc.
There are several similarities between the two systems, wouldn't you say? And what's the real difference? The source of power.
Likewise....
Using hemalurgy, you can push and pull metals. This is also possible in allomancy.
Using hemalurgy, you can see the future (though possibly differently than allomancy, we don't really know). This is also possible in allomancy.
Using hemalurgy, you can rapidly heal yourself. This is also possible using Feruchemy.
I think the overlapping is fairly justified considering what we've already seen.
It is entirely possible that Inquisitors use allomancy, but until I see something that gets rid of the possibility, I personally will believe that the Inquisitors are primarily hemalurgists.
This leaves me with the following conclusion. Instead of Hemalurgy being this complex system involving using your blood to fuel powers or something, what if it is as simple as a process that let's you 'steal' powers from an Allomancer or a Feruchemist.
It very well could be, and I actually quite like this idea. It explains fully the necessity for a sacrifice. However, it also has its problems.
My interpretation of this is that you would kill a skaa misting with a particular allomantic power and put his/her blood on a spike. Then you stick the spike in yourself and you magically gain their power through their blood. This would also apply with a Feruchemist, allowing inquisitors to use feruchemy.
However, feruchemy doesn't have the all-or-nothing limitations of allomancy, so if Inquisitors are "stealing" Feruchemial powers, they should have all of them, not just healing. We have seen no evidence of this thus far, and you would think we would have, particularly when marsh is fighting Sazed. Also, the Inquisitors wouldn't be so fascinated with feruchemy and its capabilities.
We could assume that if you 'steal' a power from someone that you already have, it would make you even stronger at it. This could explain why Vin can pierce copper clouds, just as inquisitors can, but she can't heal like them. Maybe if you stole the power from 3 coin shots, your power to push metals would be far above what a normal coinshot would have. Also, like with Marsh, if he had the ablity of a seeker, then stole the powers of a seeker, he would have even more seeker power. Brandon mentions in his annotations that the ability to pierce a coper cloud and affect metals inside the body isn't something special, it's just someone being very very powerful with that particular skill.
I originally really liked this, but the problem comes with someone who already has a particular skill. From my above mentioned interpretation, you would gain the ability to burn metals. However, if you already have that particular ability, i can't see why it would make you any stronger. The only way of doing this would be if it provided a continuous power source, which I don't see how that would work.
Overall, it's a very good idea, but I just don't see how it would work. If I am misunderstanding or you think of a way it might work, I would love to hear about it. It's good for us to discuss all options.
I really like how you defined Allomancy and Hemalurgy in terms of Ruin and Preservation. I mean, it seems so OBVIOUS now. I am steadfastly certain the Lord Ruler picked up Preservation at the Well, so, if he got that and "created" Allomancy, it would naturally be based in Preservation. The Ruin-Hemalurgy link is very well explained, so that works for me.
I was thinking about this today, Chaos, and I thought myself that it may have been preservation he touched. I'll go into my full theory over on ruin and preservation.
I still don't really like that sacrifice explanation though. Just... seems weird, I guess. More stuff to work on, then.
I've always felt that this is the weakest point in my theory. I just haven't been able to come up with any other reason yet, although if the Inquisitors actually do gain allomancy, the thing about killing mistings makes the most sense. I have a hard time believing the inquisitor allomancy thing, but I have yet to find a better explanation. I'll keep thinking.
Comatose does have something, though. The spikes are all touching. That's important... we haven't gotten onto that point yet.
My initial thought when I read that was that as the spikes sever the spinal cord, They are the only connection to the brain. If the inquisitors have to think about using hemalurgy to heal themselves, then once they lose the ability of their brain to communicate with the rest of their body (i assume the gold spike is in the chest, as the lynch pin is steel and no one remarks about inquisitors having gold sticking out of their eyes...) they are no longer able to heal themselves. Could be wrong, but this makes a lot of sense to me.
Phaz, I really like your idea, but I just don't feel there's all that much to support it. So for now, I stick with my original theory of hemalurgy. Now to work out all the bugs.....sacrifices.......mist repelling......yes
As a side note, you guys really aren't nearly brutal enough in tearing me apart. I encourage you to do so at the end of every post and I get like one thing each time. How am I supposed to fix it if you guys don't tell me what to fix? It also makes me feel kinda bad when I start picking on phaz, here....(*contemplates deeply on the matter of tearing posts apart....*)