FYI Earthgore's Arms pack also has the same light bug that Nerien'eth had where one of its pieces doesn't emit the ambient light.
The mace, maul, bow, and staff all have an orange ambient light in addition to the red smoke on the item. The shield just has the smoke - it doesn't light up the environment. Notice on the left side of the picture that the tree trunk looks the same with nothing versus with the shield, while having any of the weapons out on the right lights it up.
ZOS fixed the Neri set, so is this also something they can just flick on for a future update?