I know it can be done, since I've worked with DressNPCs before. Unless RPH is using an old or custom version of the code, it should have a "Class" collumn. If set to death knight, the NPC gets blue eyes as would a character. Also, it should also have collumns for the extra features that demon hunters have.
Update: Since we're going to be upgraded to Battle for Azeroth soon, this will also be very useful for those who'll want to create NPC templates of Lightforged Draenei, Highmountain Tauren, Nightborne, and Dark Iron Dwarves, and also the new postures for Orcs and Mag'har Orcs.. The current system of NPC templates only allows for usage of Skin color, Face type, Hair, Hair color, and Features, which are the basic and once only variables in a player character or NPC; however, that is no longer the case, as races such as the Lightforged Draenei have extra options such as their tattoos, or their rune types. It would be great if we could get this kind of update along with the Battle for Azeroth upgrade. We would also need the ability to modify the "Class" collumn, as stated in the original message, to make the NPCs have blue Death Knight eyes by setting the Class collumn to the Death Knight Class ID.
Edited by Bhalandros, 04 September 2018 - 11:23 PM.