Ardent Censer is getting nerfed because its so strong that it makes it not worth playing most tanky melee supports. Instead of nerfing AC to the ground, why not just make a new item just for them? I was thinking something along the lines of
+10% Cooldown Reduction
Active: (No partner selected or partner out of range) Designate an ally as a partner.
Passive: While within 800 range of designated partner, **Melee** attacks grant one stack of x.
Active: (Partner within 800 range) Consume 5 stacks of x to grant partner a shield of 100 (+20 of casters bonus health) and causes their next attack to hit twice. Any on-hit effects will apply to the second attack. (5-10 second cooldown)
Some tweaking would have to be done to get it in a good spot, but something like this would make tanky melee like Braum or Leona really good supports for on hit champions like Vayne/Kogmaw or for a champion like Jhin who has a set attack speed.