I am not an expert by any stretch of the imagination. I can agree that most people do not know how to properly use an edged “tool” for self-defense. I can also attest that one does not have to be a scholar in order to be effective with a knife.
Here is a link to a video that shows a man with a knife attacking multiple law enforcement officers (not sure of country of origin) who have firearms. Link: http://www.youtube.com/watch?v=75RTkGbiJpk
I don’t think using a knife in one hand and a pistol in the other (simultaneously) is a good idea at all. Use one or the other but not both, unless you are using the knife as a retention tool for the firearm. I would advise some professional training.
"All the great things are simple, and many can be expressed in a single word: freedom, justice, honor, duty, mercy, hope." -Winston Churchill