It can't be helped with the royal guards and also the king getting so much screen time plus human nature. The dread was there only when they seemed both unstoppable and totally vile and inhuman, like back when Pitou captured what's-his-name-hunter and poked his brain with the antennae. Now they have even concretely got quite human indeed, so they are just regular if strong enemies at this point. They have even been having conversation with the humans.
The fight between King and Netero looks quite promising. Coming up with the mystery of the unknown name to put some fight into the King was a good detail.