I have, for my entire adult life, carried a knife if I am clothed. I find practical uses in my daily work. (I am in retail.) A bit of history however may clear up this "Tradition"

As I understand it, The "black knife" got its name -in part- from being covert. It was worn displayed as a courtesy to ones host. It was generally concealed otherwise. Any true historians want to chime in on this though? (MAC?)

Of course, one might get into more trouble for carrying a "concealed weapon" if they chose to carry it out of sight.