During the initial brainstorming, I actually put down notes for a larger number of books. One included Little Red and Der Freischütz ("Book of the Hunt", I believe?), another contained Blue Star at the very least.
I ultimately decided to focus on a handful of options instead of a dozen or so, figuring that if people had a better idea than the defaults, they could write it in.
Divinity, White Night and One Bro, would have gone more for the angle of divinity and the Brother Gods. It would have also been an on-command nuke that deletes whatever encounter it is used in.
Birdcage was the most in-theme with Binah, which makes sense when considering they are her floor's Abnormalities. Though they were also the murderhobo route with their penchant to wander, so the Thread would have to spend effort on corralling them.
Tea Party and Tools were both versatility packages; the former with a free will and the ability to blend in at the cost of turning into monsters when triggered; the latter without the ability to disagree with Binah, but less effectiveness on the whole.
Der Frei and Little Red would have been good options honestly. They avoid most the pitfalls that non-humanoid abnos have (Der Frei might still have some trouble) and there's some great storytelling potential there, especially with how the abnos changed their nature in the main story.