[quote=@BCTheEntity]

Ah, I see. So in theory, could any given faction make preparations in order to try to counteract their corresponding weaknesses? For instance, could Machina units implement safeguards against corruption in their coding, or demons develop a means of limiting the effectiveness of holy powers against them, that sort of thing?[/quote]

Not really. It's a fundamental aspect, like fire being a high temperature. It's more a wasted effort, playing to your weakness rather then a strength. But I should really re-iterate that these are only minor advantages and this line of inquiry has me thinking you're trying to develop someone seeking to exploit this when that's really not a wise idea. 

[quote]I figured they'd all be heavily defended, not least by their extremely powerful rulers. Not so much that they all existed within the same dimension, but I suppose it works if you can't just teleport in guns blazing. That said, would each faction have their own additional dimensions to work within too, e.g. backup realms to fall back into if for some reason their capitals are completely overrun?[/quote]

Nope, there is no fall back point. 

[quote]That's fair. Since you mention them, what do the Vassals represent within the setting, aside from theoretically not getting involved in the faction war past preventing those cheap shots? Looking at Juno's title, for example, I gather she has some major role in the Nexus' metaphysics, though I'm not sure what exactly. Are they all personifications of concepts within the Nexus? Are the faction leaders all Vassals themselves?[/quote]

Juno has two bodies. The human shaped one people interact with, and a massive serpent who is coiled around the entire Nexus and holds it together. People got to glimpse that a few battles ago. As Windel had said the Vassals were never intended to be as prevalent as they had been so most others aren't as relevant.

[quote]I suppose that's fair. I'm not sure how that meshes with the way they're described within the OP; does it not have anything to do with the user's inherent potential for using them? And with that in mind, what about stealing them from another bearer in some way, like physically pulling the Eyes out of their skulls or something? Though even if that were possible, I can imagine it'd be extremely difficult, given that the powers themselves are a huge advantage.
[/quote]

Your inclination determines the color eye you receive; As in a more violent and destructive person get's Gold while a more supportive or commanding person gets Silver. As for stealing them? Can't say. 

[quote]
I suppose it'll be difficult to ask more questions about that for now, then... though I don't suppose we happen to know if the Vassals have any relation to the Great Danger?
[/quote]

As I said before, plans have been FUBARed so often we literally can not say any more on the Great Danger.

Though all of these questions are superfluous at the moment, as one has to wonder what bearing they have on your character sheet. Capital Raiding, Colored Eyes, Vassals and Capital Raiding are really irrelevant subjects for a new character. Questions are nice and all but when you have no investment in the RP it's just raising concerns as to what kind of character you have brewing.