Chapter Two is up

[DHBirr]

(I also have yet to figure out why Serenity was cloistered in her palace when she was as powerful a sorceress as she was.  What was she doing that was more important than personally blowing away battalions of youma?)

The Doylist perspective is that Serenity is a princess archetype, the symbol of the purity of the empire, and should not be seen doing anything to dirty her hands.  Possibly that was the Watsonian perspective as well, that anything like combat was beneath the Queen's dignity.  There's a historical double standard where kings are expected to lead armies, but female monarchs are supposed to let other people fight for them.
...
It's possible that by the time the battle came to the Moon, the war was already lost.  Possibly as a result of the above attitude, if it existed.  I mean seriously, it was all a bit like Berlin in April 1945.  It's possible that Serenity was casting the spells to send her descendants into the next age, or to create the spell that sealed Metaria.  She was cloistered so that she could do the work to send a light into the future.  After all, if you use the Ginzuishou without a plan first, who knows what sort of problems you could cause?

A possibility that occurs to me is that, depending on how her magic worked, "cloistered in her palace" might in fact be the most effective place she could be for "blowing away battalions of youma...." I mean, suppose she had her best-prepared pentacle, or whatever she used, at a the lunar equivalent of a node within the palace, and when standing within that magic circle her spells were amplified so she could drop pinpoint annihilation on enemies thousands or millions of kilometers away? Her advisers wouldn't, then, want her to be anywhere in a battle that gave her less targeting range or precision than that.  It needn't work exactly on those terms, but anyway following the concept that from inside the palace she was able to use her magic more powerfully than when out on the front lines.

Edit: In short, she was the heavy artillery. You don't put that in front of the infantry.