Huh, I took pekiti tersia (it's a close-quarters knife fighting style from the Philippines for a number of months. One thing they emphasized was keeping your other hand the fuck out of the way of the knife.
There were a few guys like this one in the class. They spent a lot of money on knives, yessir.
I had a friend who collected swords and who occasionaly had a large knife on him. He would quite often take it out and quickly brandish it, pointing it at your neck or something like the Scarlet Pimpernel or some shit, while making a stupid face, trying to look cool. Occasionally, he would sing lines FROM the Scarlet Pimpernel musical.