If you are going to nerf Relic Shield and upgrades, don't nerf the health.
Relic shield offers relatively little for the tanky support aside from the healing proc and the base health. If you believe that the sustain is the problem, nerf the healing, but don't nerf the actual health value on it. Compared to spell thief and ancient coin (which has been eyed as getting a buff), 75 health > 50 health is a pretty substantial nerf to a support class that needs to be relatively tanky when compared to the other support archetypes. Relic shield has already been nerfed to make it less appealing to the ADC, please don't make it even less appealing for the support.
Sincerely, a predominantly tank support main.
health reduced to 50 from 75. That's a 25 health reduction.
health reduced to 125 from 175. That's a 50 health reduction.
health reduced to 350 from 500. That's a 150 health reduction.
, simply because he can proc its passive trait from relative safety.