This episode touched on many interesting subjects.

The first was resistance to change, no matter how potentially beneficial. The village elder refused the Maou suggestion and prefer to stick with the old way. It's a sort of "while it's bad, i don't want to risk it becoming worse" sort of mentality. It wasn't until the Maou gained some leverage by becoming the teachers of the village's "nobility" that her suggestions was heeded. This touch on the need of playing political games in order to achieve your goals. I expect for this particular subject to come back many times in the series.

I agree that the sister maids scene was done very well. While people like Hero see a distinction between slaves and serfs, the head maid offers an outsider perspective when she doesn't feel the need to distinguish the two. When it comes down to it, Serfs doesn't have any freedom to choose. The head maid ultimatum to the sisters did two things in my opinion. First, it establish the ability to choose as the thing that separate human from lower life forms. Second is that she told the sisters to apologize after chastising them for their action. They did what they need to in desperation, but that still doesn't make it right. The older sister ability to recognize when a choice is given and the willingness to accept the consequences of their action made that a powerful scene for me.

I also agree that the hero scene is good. It's pretty much established that the hero is not very smart, but he is definitely perceptive. He's rational enough to admit fault in logic he believed all his life and practical enough to simply move on.