Positioning his body in a wider frame, Rex looks at Lady Lauren directly into her eyes keeping their eye contact intense. It's more like a settling of dominance that these two are fighting for, the winner will have an advantage mentally.
The woman called Kiera is locked in her spot with Kyran's black spear on her neck.
Making a sudden move in this kind of situation where the tension is very high will be a bad idea, Kyran might just slash her neck off if she decided to test him. But that's not the only thing that makes Kiera stands frozen like a statue.
Aside from the surprise that Kyran manage to bypass their senses, Kiera can feel that her spirit got suppressed by the darkness coming out of Kyran's body. She literally can't use her spirit to fight.
Calling out her spirit shadow might make her leave this situation, but she can't.