Miasma Priest and Defiler are treated as separate forms and have a different moveset from what I recall, one fought Yixuan and I don’t believe is stated to be easy while the Defiler was stated to be easy thanks to the aid of Yixuan by Orphie and we know said characters the Defiler clashed with are immensely inferior to Yixuan.
The Miasmic Fiend as you mentioned struggled against Spook Shack and was only a issue due to its regenerative ability, otherwise it was against emotionally affected Yixuan that could be said she wasn’t at her best. It’s lore is pretty much that’s its just a imitation and a mere pawn.
Fair point on the disciples but Ju Fufu and Pan Yinhu I feel lack the hype Section 6 got as a group.
I doubt Miyabi spoke from a sentimental reason given she flat out chose him because he was strong and I don’t know the context of him saying Miyabi Vs 100 of him, could he just be joking while putting down his own strength? Harumasa still beat a Miniboss Ethereal, Thracian, while immensely progressively weakened state, repelled Nineveh with Yanagi, fought second form Bringer and is hyped up by the serious Miyabi.
I could more understand Yanagi and Soukaku but I feel Section 6 can far downscale from VH tier until we have reason saying they’d be in line with other Agents.
Also very nice on the 8-A ZZZ, now I can make Bringer, Nineveh, Gepetto and Isolde.