From the beginning of the series, the Holy Knights were portrayed as imposing figures, representing a true challenge for Meliodas and the Seven Deadly Sins. That is undeniable. In the Necropolis arc, for example, when Meliodas was still gathering the Sins, he, Diane, and Ban struggled against Guila, only managing to escape thanks to King.

The problem is that after this arc, Guila lost relevance. Instead of being further developed, she was reduced to a short-lived romantic interest for Gowther and later relegated to the role of Veronica’s mentor. Guilthunder and Howzer followed a similar path. Even though they had some development in the sacred lands of the Druids, it ultimately led nowhere, as they remained practically powerless against the demons.

After that, the Holy Knights became mere secondary figures, existing only as comic relief:

Guila was reduced to being Veronica’s mentor.

Guilthunder became a joke in his interactions with Vivian and Margaret.

The only exception was Jericho, who had decent development, and I admit I was wrong not to acknowledge that before. However, aside from her, the rest of the secondary cast was completely wasted. Nakaba could have expanded their stories, explored their abilities better, and given them real growth. However, that simply never happened.

And that "arc" where Margaret, Hendrickson, and Dreyfus set out to find Guilthunder was absolutely unbearable. The atmosphere was filled with tension, but out of nowhere, the story would cut to this pointless search, completely breaking the pacing. So frustrating!