I based the illustration on the cover of my book, Bowie Knife Fights, Fighters, and Fighting Techniques, on this sculpture by J. P. Molin, displayed in Göteborg, Sweden. (See also here.) Commonly called "The Knife Fighters," its Swedish name is "Bältespännarna," which translates as "The Belt Fighters." This type of knife fighting, in which the opponents are bound together by a belt, is described in The Alhambra and the Kremlin: The South and the North of Europe (1873) by Samuel Irenæus Prime.
Another very remarkable memorial of past times and customs treasured in the [Christiania, Norway] museum is the girdle and the knives which the gentlemen of Norway used in the good old days, now lost, when they pitched into one another in duels. First, each one of the combatants took a butcher-knife (we call them bowie-knives now), and plunged it as deep as he could into a block of wood. The blade, so much as was not in the wood, was then wound round tight with strips of leather, and the knives were cautiously drawn out, and each man took his own. It therefore had now a longer or shorter point, according to the strength he had to plunge it into the wood. Their girdles were then fastened together, so that they could not get away from one another. Now they went at it hip and thigh, cut and slash, till one or both were killed. If modern duellists were put to such tests of strength and courage, there would be few challenges.Interesting that the man of superior strength, able to plunge his knife deeper into the wood, is further advantaged by being allowed that much blade to work with in the duel. Sounds like the viking notion of fairness; i.e., "Sucks to be you."