lol , all the outfits are editable what make that outfit unique.
While all outfits can be edited outside of the game using modding tools, outfits like hongmoon ascension can also be colored inside of the game, which makes them a bit different from the regular wear-and-forget common outfits, like the default hongmoon uniform and most older outfits. So when you see this outfit's main texture dds, instead of the colors you see in game, the image is in blue hues, very similar to how normal/bump maps look. I'm assuming that unlike regular outfits which come with all their colors on their DDS, these get their colors from the material file. You can still edit the outfit's alpha without problems, but I have not tried editing the blue hue itself, and I doubt we'd be getting the expected results if we do so. As all actual colors come from somewhere else.
So TL DR The blue* hue file is this outfit's specific main color file. And you will see similar hue patterns on all outfits that can be recolored inside the game.
*EDIT for the sake of correctness. I checked another outfit's .dds and it comes with not a blue, but purple/pinkish hue. So while the basis is the same, not all of these are blue. Wonder if there may be other colors.