Hello,
This might sound horribly obvious...
When using a set like:
Ebon Armory
(2 items) Adds 1206 Maximum Health
(3 items) Adds 1206 Maximum Health
(4 items) Adds 4% Healing Taken
(5 items) Increases Max Health by 1000 for you and up to 11 other group members within 28 meters of you. This bonus persists through death.
(thanks ESO HUB!)
You have to be in a group, right, not just close to players in the same faction?
Tankz,
Z