Are you referring to the Whetstone charm? It allows you to parry off enemies/bosses once per jump and deal considerable damage. I only run on current patch but I haven't heard of any glitches to get parries

You can buy in the Porkrind's Emporium store the Whetstone charm that it allows the player to use parries to deal damage to enemies

Maybe the question is the same one I have: in Funfair Fever, how did jason2890 get 5 parries on a balloon in less than 1 second?

I believe what you're referring to is a glitch that was patched out in the 1.2 version. You could parry all the way through solid pink objects without taking damage