I have a hand to hand combat field manual from the U.S. Military (got it from a surplus store) and it details silent kills in the section about removing sentries. In pretty much every single maneuver it says to induce shock before killing the opponent IE- hammering the hilt of the knife into the kidney, neck, or head, and then finishing with slicing the throat or stabbing vital organs in the chest. My favorite of these is the "Belgian Takedown" where you grab the target by the ankles and throw your shoulder into him. His face slams into the ground, inducing shock, and then you finish him with a strike to the groin or the back of the head.
But back on topic. There's a difference between trying to silently kill an opponent with a knife and actually engaging in hand to hand combat with knives. When it comes to hand to hand combat with knives it is dirty, fast, and vicious fighting that can come down to a single good strike. In such a scenario you want to try to use anything to your advantage, if you can intimidate your opponent by shouting like a madman then by all means you should do it. And if you can hit him with a strike to the throat then do it. Also, about striking the belly, they were trying to show the damage that the weapons can do to a human body moreso than trying to demonstrate their proper us.
And even more back on topic, what do you guys think of the match between Hannibal and Chinggis Khan? I thought it was an extremely unfair match given that it was a battle between bronze and steel.
