a) ever doubting the Ancient Dragon's a phony
b) thinking the Watcher and Defender were Nashandra's allies
c) why Amana (because the milfs are basically Nashandra tranquilizers, that's why. still don't get why the place is crawling with Lindelt's cleric soldiers though)
d) not really figuring Vendrick's last plan to foil Nashandra's ambitions (as I don't see the connection between the Throne of Want and the Giants' Kinship)
Anyway, I never fought Throne Bros and Nashandra in a row so the cutscene footage surprised me. Gotta try that one'a these days.
Side note, something that crossed my mind about that cutscene: it's Nashandra who crosses the fog gate, making you (the player), the game's final boss from her perspective.
They should have reversed the HUD with the HP bar below being "The Throne's Heir" and Nashandra's on the upper left.