I'm watching Shark Week right now on the Discovery Channel. They're not paralyzing any sharks in today's episodes.
You may be thinking of the Silky Shark. It is a mostly deep water tropical species that rarely causes any problems for humans. I have seen video where Rodney Fox, (often seen on shows about Great White Sharks) grabs these sharks by the tail and then turns them upside down. They then go to sleep.
I would doubt this move should be attempted on just any shark you may encounter, and having some experience dealing with sharks may be a prerequisite.
Sharks aren't smart enough to know whether you have a weapon or not. Fish in general are not too bright. If you poke them with a stick or they see you jab at them, they may back off, but they are not thinking, "wow, I better watch out, that guy has a sharp stick."