If you go into a fight tooled up you've got to use it. To flash it about and hope you scare the other party away does'nt work (as the statistics show).
I don't carry a knife, although I was caught up in a knife fight in January which was the 3rd time I'd come across a knife but the 1st time I've seen one used, I don't run with those sort of people I just have to deal with them via work. From what I've heard off people who've been stabbed or witnessed stabbings, is you don't see the knife, it's that quick. Stab, stab, stab and off they run.
I don't care if you SAY you're carrying a knife for protection, you belong in jail if you're caught with one.