Witnessing the frozen hell created by Silvia was a unique and disturbing experience for many. Although this was not the first time, the squad had seen a massacre, the eerie silence, accompanied by the ice statues of people who used to be alive, was quite tricky to process.
Morales wasn't too affected, just like Claire. In Morales' case, his ability had much more nasty and brutal results when he managed to hit a person with it. In Claire's case, the violence she had seen in her life had made her quite desensitized to this sort of thing.
Silvia, the person in charge of the frozen body show, could barely stand up. For Silvia, unleashing an ability like the previous one was too stressful. As talented as she was, Silvia lacked the technical knowledge, training, and control to use her powers well.
Due to this combination of factors, Silvia, who should theoretically be as strong as Revna, was significantly weaker in combat, and her performance was less durable.