[The Might]

A Little Green, as long as there is a book out there called "The Science of Middle-earth" I wouldn't be so hasty to discard the whole scientific explanation part. So no, to me you're not making that much sense.
Tolkien was no the kind of person to write stuff without thinking it at least a little bit through and everything there has a certain explanation.

Now to the dragon idea, the basic theory in pretty much all newer dragon works is that the fire is only created in their mouths through the mixture of two separate chemical substances. And this makes quite a lot sense. Anything that can be pierced by a sword isn't probably capable of taking that much heat. Thus, a dragon himself wouldn't really need to take that heat himself.

Aganzir, indeed good criticism. I had not really taken that into account. As I am not really an expert in material qualities I can't really say what would work, but if workers in foundaries have something like that it could be an idea.
Although I don't understand what you mean by "lesser spirits", in CoH they are "great spirits" implying Ainur.

And I also see no reason why they should not have been. After all Sauron was one of the most powerful Maiar and one of the best smiths. Their weakness is relative.