Can we get some sort of attack or item that goes through shields?

Purpose of damage is to lower health bar. Purpose of shield to resist lowering the health bar temporarily.

You are asking for pure damage, not true damage, PURE damage. The only thing in the game ignores shields and goes straight to HP are the fountain turrets. No thanks, people always cry about Vayne and Fiora; there is no way this would be balanced in any way.