How about "The Duellist's Companion" by Guy Windsor? It's right over there on my father's old Army footlocker -- along with the author's "The Swordsman's Companion." And I just received today, as a gifte from my Goode Wife, "The Complete Book of the Epee."

Should "Shane" decide upon a challenge I would remind him that the challenged party has the choice of weapons and the condition of the duello. I would also remind him that I am a fair-to-middlin' shot with rifle, pistol (including revolvers), shotgun and bow, and that I used to teach hand-to-hand combat.

Moreover, I would set the duel as Third Blood

But I am not too concerned, as he would have to send his friends "call upon me" and I'm not sure he has any. Besides, I'm certain writing the initial note would tax his abilities to their limits.