Frieren and Fern are the only magical girls that I care about.
Damn, I'm glad that I've read the relevant manga chapter a long time ago. I forgot about this arc and all its little wonders: screwing with the water so the Stille won't get near it, the battle junkie in Fern's party, and how amazing of a mage Fern has become. Why use more advanced spells, if the simpler ones are more reliable?
I am in the same boat as you. I read these chapters long enough ago that I almost feel like an anime-only. The only character I remember pretty well from this arc is Denken (plus a certain character that has been teased in both OPs now) and he has been great so far. I really like the VA they have for him.
The soundtrack and background art has been phenomenal for this show all season. In a recent Sakugablog post, they talked about Frieren and the stellar team of animators/staff they assembled for the production. One person they give a lot of credit to is Seiko Yoshioka, who is credited as a concept artist for the show. However, it seems that her influence has been enormous on the overall art direction and she has had a significant role in expanding the imagery and visual lore that we see within the world.
Overall, Frieren has not missed all season. Frieren was one of my favorite manga and it has also become one of my favorite anime (so far).
Also, I wish we knew how Fern's group did it, but it isn't in the source either. I actually went back and checked because it was bothering me too.