Dealing with these monsters didn't take up much time.
Strictly speaking, Mary tends to lose her nerve only when faced with humanoid enemies. Against non-humanoid monsters, she charges straight in, slashing away with her Magic Shining Sword before finishing with a flurry of attacks from the Kalya Great Sword. In no time, she had broken the metallic beast down into scraps.
It's clear that hero training in the Hero Cemetery was no waste of time. However, her hesitation when dealing with human opponents was a problem.
As for those two old men...honestly, how much trouble could two beings, barely different from zombies and unable to appear during the day, possibly cause for Duanmu Huai?