Just a quick question concerning imperators. Why is it that they only have 15 points as opposed to the normal 25? Is it because they can do imperial miracles?
Imperators look at Excrucians kind of like humans look at poisonous snakes. The problem isn't power—-the problem is that one day you turn around and there's this cobra looking at you, and then you try to do something and you're dead.
So the Imperators get Powers, who can act on the Excrucian time scale. They're like dogs or mongooses or something.
Your 25 CP mostly represent ability to act on that time scale. Imperators have limited CP for the same reason that humans are bad at hand-to-hand combat against cobras.
Note that this example is not definitive; it's just your random analogy for today. It'd be equally fair to say that Nobles are super-awesome spies and the Imperator is Q, or their giant bodyguard, or their tank.