Hey, I tried to kill the Infected bat with the knife only and with six full health restore and two more green herbs, I hited 31 times the boss, still not dead. If anyone have succed to kill him or any tip, that will help me.

I finaly killed him with 37 knife hits.

The Bat seems to be different in the HD version over the Original.

Pretty sure it was the Bat that was altered however, and not the Knife, as the Knife seems to function identically to the original in almost all other situations.