That naturally leads to the question: How many people could Hitler have killed between 1939 and 1944 if he had been facestabbing exclusively?
We'll set aside zero hours per day for sleep (he's a busy guy and hopped up on amphetamines to boot), and assume that travel time between victims is nil (the SS is herding the entire population of Europe towards his stabbin' arm). The force needed to crack a human skull can be averaged at around 473N (not going to bother with psi for the sake of a joke in terrible taste). Now, a human can punch with more force than that, but Hitler is a fairly shrimpy guy. Still, he has a knife, so the force will be concentrated on the point. Let's assume 1.5 stabs on average to stab someone to death. Measuring the time it takes for me to deliver 1.5 overhanded stabbing motions gives around 2 seconds. So 0.5 stabbing fatalities per second.
Ignoring actual dates for the sake of simplicity, there are 189216000 seconds in the time period we are considering. That equates to 94,608,000 stabbing deaths over six years. If he slept for 4 hours per day, he would "only" have stabbed 78,840,000 people to death over the time period measured.
The conclusion is obvious, ladies and gentlemen. If Hitler had perpetrated the Holocaust by personally facestabbing people, he would have killed 7.1 times as many people as Nazi Germany did in real life.
I'm so, so sorry. Both for the topic and the terrible, sloppy maths.