Cygnuses are unavailable.

Yep, this one:


In the video it looks like she is quite literally gearing for war.
She's been overseeing the events of the alliance for a while now, and hasn't been THAT much use, outside of finding the World Tree or liberating Azwan.
Ereve has been attacked before, but her Knights have always managed to fend it off, and then comes someone who is too powerful for them to fight, who kills someone dear to her. It seems clear that her first thoughts would be "We need to get stronger, I need to get stronger"

And then she goes and makes a contract with Kyuubey and transforms all Magical Girl style. "your wish has surpassed entropy"

Something that comes to mind too is that she's always been very passive, far more than would be acceptable from a nigh uncontested ruler. I've attributed this less to incompetence and more to lack of power though, as the Cygnus Knights' low max level is actually reflective of how strong she really is at that point and you have proof of this from Future Ereve and this coming revamp. Perhaps it could be said that she's had enough of having people rescue her all the time and she's ready to strike back, which would make for an amazing storyline if it involves all of the main players (Resistance, Lilin, heroes like Phantom/Mercedes all come to mind as they have more ties to Cygnus than most of the others).