The knife as much as it could be intentional seems more than likely unintentional - the knife is just feeding back more "hits" due to higher frame refreshing meaning the game is refreshing the actually time it's on the enemy more often. I'd still assume it as a glitch, or treat it as a glitch - which would then have Glitchless runs capped at 60 FPS for fairness in that regard but glitched is anything goes as per it starts. In Any% glitchless - knife can still be used but the game needs to be limited to 60 fps - and there needs to be a way for it to be confirmed in 60fps (maybe flashing/changing settings at the start of a run to confirm).