Armor.xml

I noticed that 3 of the 4 Dragon Priest masks added by Dragonborn were missing from the XML, so I added them and reworked the rest for balance. Priorities: 1) maintain an equal number of heavy and light masks, 2) ensure that the material type matches the mask's coloration, and 3) make Dragon Priest masks preferable to most low- and mid-tier armor types (in accordance with their status as high-level artifacts).

TL;DR I added missing masks.