I wonder what they can possibly offer Aizen for him to give a damn. There is no reason for him to help them. Maybe they'll promise him Hinamori's death?
Man, aside for the Aizen's trolling, yet again useless chapter.
Nothing is missing if you actually look at the panels and it's kind of obvious why he can use the black getsuga with his long sword is it not.
I read the chapter one more time and there's only one sword in Ichigo's hand, unless his sword is now two swords combined togheter and it's his bankai.