She could telekinetically freeze them all, and do whatever she wanted. Dark Phoenix is not weak against mental powers, it was the Jean Grey consciousness that was seduced, which resulted in the creation of Dark Phoenix, who went mad when she asserted herself and realized she was being manipulated. She also enjoyed the rush of embracing her dark side, as it was all about unbridled passion and rage. She cannot be killed, when she "destroyed" herself on the blue area of the moon, it was her own doing, and it was obviously not the end of her, it was just something that Jean would have done to protect her friends and the universe, and it also allowed the Phoenix to shed it's dark persona.