Yes. We fight serious and deadly duels. The challenge can come at any time from these our mortal enemies: Ego! Falsehood! Prejudice! Compromise! Vanity! Cowardice! and Ignorance!
Our weapons of defence against these are: Self-control! Truthfulness! Understanding! Firmness! Humility! Bravery! and Knowledge!
I discovered this when I took up fencing in 2001. It's a reasonable, if
somewhat romantic, question. And this answer comes from what appears to
be one of the few schools that teach classical, or historical, fencing
as opposed to Olympic fencing. The main difference being that Olympic
fencing is basically a sport, and if you were to follow its techniques
and principles in a real duel you would surely be killed, whereas
classical fencing is a martial art, such as would have been practised
by young men centuries ago as they equipped themselves for self defence
and general aggression.