Yeah! 9th is back. Like a cat with 9 lives.
As mentioned previously, the 9th's survival probably has to do with Deus stabbing her. However, the 9th we see believes that it didn't actually happen (she was puzzled). What I am thinking is that the 9th was "disabled" and Deus merely made another existence like the 9th (sort of like Akise). The 9th that died was an illusion and the 9th that is alive is the one Deus stabbed.