These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fridge Brilliance - A minor example at the beginning - Yuuhi and Noi even fight over a lizard's "retreat gimmick", but at the start all Yuuhi could do in a fight, was use his powers to run away.
The Master, Inachika Akatani, lost his precognition and other powers because he drew upon the akashic records - the Mage has literally destroyed the future in order to travel back in time.
Yuuhi's developed domain control Babylon, enhances his movements while miring his opponents. Since it only enhances what he already has, it requires him to have a strong baseline in skill, strength, and an agile mind to get the most use of it. Skill, he inherits from Hangetsu. The rest of it clicks into place when he mentions digging all those trap holes helps him build strength and think. In short, he conducts his training arc right under everyone's noses. Even scarier when you realize the slowing property of Babylon mirrors the pitfalls of his traps. The airspace around him effectively means he's fighting in favorable terrain wherever he goes. Batman would be proud.
The Biscuit Hammer and the Blues Drive Monster are so patently ridiculous because they were made by people whose childhoods were brutally cut short by their own actions. They frame their war as a game and make weapons with absurd appearances and silly names because they never properly grew up, mentally. Quite tragic upon realization.
Hisame remembering the moment she decided to do her best for Sami.
Hanako's flashback monologue of her relationship with Tarou.
The last page of Chapter 62, when Samidare admits that she loves Yuuhi more than she does the Earth (this makes a lot of sense in context). If this doesn't bring a tear to your eye, then you have no soul...
One of the most out-of-left-field and awesome reveals ever:
Anima: Do you see it? The Anti-Biscuit Hammer Celestial Body Dwarf Counter Weapon. Blues. Drive. Monster.
In chapter 58 Samidare, after the Blues Drive Monster is destroyed, psychically takes over the debris and makes a humongous version of herself and fires the ultimate falcon punch, obliterating the biscuit hammer.
For the series itself, the entirety of the final battle with Animus. And within that the Beast Knights actually beating Animus on their own with minimal help from Samidare.
Never Live It Down - The Ojou-esque Snake Knight fears she'll never marry now that Anima's sudden teleportations have revealed her darkest secret: She's a closet Cosplay otaku! Naturally, no one else cares or notices.