Would an item that either stops or weaken shields (like griveous wounds prevent heals) be a good addition? Shields are almost everywhere, and sometimes seem a little excessive, so some form of counter that the support does would be a nice addition to their game impact, that is not buffing their teammates. Thoughts?
yea they exist and every champ can get them and every champ has it built into their kits
its CALLED DAMAGE
for example gives UNIQUE: Grants a decaying shield to nearby allied champions and yourself for up to 2.5 seconds, absorbing up to 35 +35 per lvl (based on level) damage (90 second cooldown) (600 range).
and lets say its the supports 4th item in... so lvl 10-12ish so it would shield about 35+350 for total of 385 shield for 2.5 seconds... lets take a popular damage carry champ at lvl 11 
hits you with his ult doing 300+150% bonus ad plus For the next 15 seconds, Yasuo's Critical strike icon critical strikes ignores 50% of his targets' bonus armor
i think his damage would out exceed the amount of shield that gives
If shields are truly a problem that needs its own counter, I might suggest having % damage deal double to them (or just a higher amount).
