Stupidity: Shaun thanks Seiya for revealing the weak point of the armors of the Black Knights, but Seiya didn't actually do anything; the armor malfunctioned on its own. If Shaun is able to deal strikes with her chain precise enough to target a small box on the back of the enemy's neck, one would argue that she could have easily hit any other vital point the armors leave completely unprotected - especially since she showed also that she could elude their shield commanding the chain to take a sharp turn around it - which hit the supposed weak spot but didn't do anything, contradicting what is shown later.
Stupidity: In the original, the knight of the Phoenix suddenly appeared during the arena fights interrupting the show and stealing the Gold Cloth. In this remake of the saga, Sienna/Saori Kido leaves the arena by plane during a bombardment that occurs way before Nero/Ikki arrives to steal the Cloth. There is no reason why she would fly off in her VTOL without bringing the Golden Cloth with her, then (there's a lot of time for that). Instead she leaves it for the 4 Saints for them to "protect it", against a whole army and on foot in the middle of the desert.
