I found out in the demo that after you slash twice with the knife, instead of waiting, you can press the guard button for a split second to cancel the delay and do the double-slash again. You can chain the double-slashes together by guarding and slash freely like in Resident Evil 7. This increases the knife´s potential damage per second.

Made a demonstration on my Twitch:

Sorry if I broke some kind of etiquette: just want to be helpful to people.

I can confirm it's still present on the PC release version, you can just spam guard and keep swinging the knife (sometimes even stunlocking enemies / bosses)

Here's a video on PC (Steam version):

This is also present in the PS5 version, been having some fun with it on the first set of enemies

Can also confirm Xbox One version. Seems like a fun little exploit