Good news - thanks to your early feedback, we got this fixed during release candidate testing, so a correction will release with Monday's update.
The perks of a pre-release week! :D
BTS facts: Turns out that particular part of the helmet and the 4 lights in the chest had exactly the same base colour (a side-effect of creating a base dungeoneering plate armour kit to support lots of different variants). That's fine on the player, as each kit piece has its own set of recolour values, but proved a problem when adding it all together on these prerelease NPCs, that needed to ship sooner rather than later. Our lovely character artists have consequently created an NPC variant of the armour set with recolours and textures baked in, so they can happily function in conjunction.
Second fun fact: Turning off textures does absolutely nothing to improve performance. (The texture cache is loaded into memory regardless.) Would be nice if we could remove that option and phase out poly colouring as it would simplify development.