I've always found it interesting that higher difficulties basically require one to move closer to the boss, rather than farther away. It seems backwards, in a sense.
Also: Stage 6 SA:
Orin's Spell Card has a weak spot approximately ten pixels square away from her sprite, where one may stay for the entire duration without being hit. Even on Lunatic. There's also an Apollo 13 moment with Utsuho. One of her normal attacks can be dodged by going into that sphere she's holding. Granted, the extra Graze is essentially not worth it anymore due to the lack of Points to use it on, but it's still interesting.
Also: Stage 6 SA:
Orin's Spell Card has a weak spot approximately ten pixels square away from her sprite, where one may stay for the entire duration without being hit. Even on Lunatic. There's also an Apollo 13 moment with Utsuho. One of her normal attacks can be dodged by going into that sphere she's holding. Granted, the extra Graze is essentially not worth it anymore due to the lack of Points to use it on, but it's still interesting.