Both Ash tail and Heavy plate sets are label as being heavy themed, to me they do not appear to be heavy themed at all, they fit the color scheme of dusky accessories perfectly as opposed to heavy themed ones. Not sure if this was an error or that I fail to see this heavy themed-ness of it all.
Something I noticed.
Lots of players have different graphic settings - and these settings are influenced by a variety of factors. Monitor preferences, in-game graphics levels, and so on. Most importantly, the human eyeball can't be trusted - and opinions of what matches and what doesn't varies greatly between each individual person. Wiki editors try to look at the raw color codes to classify items into color themes. This can be difficult due to gradients. Wiki editors can make mistakes, so if you REALLY feel like something is amiss, compare color codes and fix it yourself :D
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Several color styles share primary/secondary/tertiary colors, so check the Color Style page on our lovely wiki if this "sharing" is contributing to confusion.
I looked at it again and I see where it would appear to be heavy themed, but then I noticed that heavy only has one grey in its color pallete and dusky has 2, both ash tail and heavy plate have 2 different shades of grey on them, but they also have small portions of the dark heavy theme red. I am thoroughly confused as to what color scheme this is...
Well of course heavy plate set is heavy. You can't have something named with heavy on it and can't let it be heavy. Should of called it dusky plate set