Nasu can be good when he doesn't give a fuck about pandering to the fanbase and writes whatever he wants (ex. Kara no Kyoukai). He goes full retard when doing waifupandering for easy bucks (ex. the entirety of the Fate franchise).
Existentialism, fear of the unknown, fear of the future, suicide, dual personality/schizophrenia for themes, murder psychology, fantasy and magic aspect diluted into the themes, coming of age story, love story developed over several years
Rape as a meme, teenager male selfinsert MC, love story over a few days (kek), chunni vampires, twin maids, basically Twilight for boys
Huuuuh, Battle Royale, fucking King Arthur for more mana, Servants have classes and characters sheets like a fucking RPG game, coming of age story (sort of, I guess...), bullshit love story over 15 days (kek), muh superhero