There's no reason to nerf this skill at all. Nb already has the lowest healing from all classes and most Nbs use the invis Cloak to begin with. Builds which utilize Dark Cloak already got hit hard by nerfing minor protection and minor maim and now the healing gets nerfed as well despite nobody complained about that skill in PvP or PvE nor is it meta anywhere. It makes zero sense to nerf a skill which is already used only by fun builds and not by competitive builds.
Some classes are completely forgotten (like Nb and stamdk for example) by the dev team and meanwhile Templar gets a huge rework. Why only Templar and nothing else? Almost all vanilla classes have huge issues getting through all the defense powercreep from the high end classes (warden, necro mostly) and would need a proper rework like Templar did (or just give them their old toolkit back with proper dots, a healing debuff, no cast time nonsense on ultimates, counters to armor stacking like old mace passives etc if you are too lazy to give us a rework).
Some classes are completely forgotten (like Nb and stamdk for example) by the dev team and meanwhile Templar gets a huge rework. Why only Templar and nothing else? Almost all vanilla classes have huge issues getting through all the defense powercreep from the high end classes (warden, necro mostly) and would need a proper rework like Templar did (or just give them their old toolkit back with proper dots, a healing debuff, no cast time nonsense on ultimates, counters to armor stacking like old mace passives etc if you are too lazy to give us a rework).