[i]"I will respect the weak and defend them."[/i]

Kalaya steps to the side, opening up space between her and Fengye. She's not abandoning the scribe, only moving to make it so that the phantom has two targets to pick from should it chose to attack.

[i]"I shall give mercy unto those who ask for it."[/i]

Her sword is out, held at the guard. She won't strike first; because what if the phantom is just looking for help? But if it lunges at either of them she is ready to leap in at the instant. 

[i]"I shall not recoil before my enemy and will be the champion of the Right and Good against Injustice and Evil."[/i]

Well, that one requires no explanation.

You ask why she doesn't break and run? The answer is right before you. It's a simple one:

She's sworn not to. Three times over. 

What's more, she's fairly sure she can fight this thing if needed. She's done the training, for what [i]that's[/i] worth in a real fight. But she also doesn't really know what kind of spirit it is - and is therefore giving both it and Fengye a chance to resolve this peacefully.