One element of
Perfect Shielding, what many people miss, is that the
recovery frames are dynamic.
If you parry a weak hit, the opponent only gets a few frames added, so that you can only punish with something of equal speed. But if you parry a strong hit, you get enough frames to answer with something as strong.
Here is the explanation in one of the Treehouse videos:
https://youtu.be/qFvucxGGy0A?t=1m34s .
So if you parry a jab, you only have time to answer with a jab yourself or something of equal speed. This could mean, that hitting an shield with a weak attack has much less consequences. While parrying a very strong attack, can give you a lot of benefits, with the risk of miss the timing and get hit. Could be a great risk and reward mechanic.