The knife is the "great equalizer."  An opponent with a knife can defeat you, no matter what level your skill.  This is the "knife wielder's edge."  Once a knife is present, anything can happen.

In attitude, it is transparent.  It reflects and magnifies the personality of the wielder, rather than changes it.  It can be forceful in the hands of the thrust-and-kill attacker, or subtle and tentative in the hands of one who prefers to hit and run.

There are some who are adept at throwing the knife.  Others shudder to think one would be thrown.  My practice is to use a fighting knife for fighting, and a throwing knife for throwing.  In essence, they are two different weapons. Regardless of what you're holding, throwing should be done only when the hit is certain.

Responding to your feedback, I am including a video clip which provides some insight into defensive knife flow, including use of hands and position as elements of strategy.  This clip is, excerpted from our instructional video Sticks, Tricks and Useful Bits, which is no longer in print.  You can find the entire video online at Youtube 

Remember, knife is a complete martial art in its own right.  All this clip represents is a glimpse into fundamental concepts.