Mira was surprised that she now has to face a combat mannequin on top of the pain in her soul, pressure bearing down on her, and intrusive thoughts. She wasn't too worried about the current battle, but she was definitely thinking about how shitty these fights might get another 100 steps from now or even more.
Mira also knew there was more to this combat mannequin than meets the eye. For the last 100 steps, Mira has been forced to die in order to continue. She found it strange that all of a sudden, this staircase would start being benevolent and allow her to kill others for the sake of descending the stairs.
The only thing she could do at this point is engage the mannequin in combat. Unfortunately, the space was too narrow for her to bring out her scythe, but that didn't matter too much.