The demons are at way too much of a disadvantage here. Given how effortlessly she defeated the doggo in chapter 1, she's at least a relatively strong demon, but...
The prayers of a first day saintess-in-training are enough to make her collapse, a simple medical herb or potion causes significant injury, and they don't seem to have healing magic of their own.
They need to show something that the demons have an advantage on, otherwise this war is going to end in a completely one-sided loss.