Mitsuru kept her eyes on Halt when she replied to Etna "I'm not going to say I like it, but it's not my place to pass judgement on it." Truth be told, Mitsuru did wish a few certain people would end up as a Prinny.
When Halt yelled at her a fierce scowl crossed her face, and she summoned her Persona to encase Halt in ice. It wouldn't freeze him, just encase him. He would be unharmed, but very cold.