Unlike her comrades, Minfilia chose against attacking Palitutu but only because there is a much bigger cost than the first time Ultima was used. It hurt and they were saved thanks to her Limit Break kicking in but she doubted that she could call it again now. So she had to think quickly before it was too late. If Crystal Knights like herself could manage to protect someone at least from Ultima's blast, it would logically be a healer...one who knew how to cast Life.

In other words: hello Jade, there is a woman heading close to you as she casted Shell on the party just as a precaution. Thanks to her Crystal Shield ability, she can absorb the upcoming Ultima attack AND protect another from it.