That's probably because those scenes are too realistic. Rather then being full of aggressive fighters who constantly attack each other in a flurry of blows in a charged dramatic fashion, they show fighters being cautious and thinking about what they will do (as one is liable to do when one's life is on the line). They also who moments where both fighters have less than stellar technique, screw up and mutually retreat. The anxiety of combat is what this movie captures perfectly. This is shown very well in the first scene where the man who gets stabbed is clearly scared for his life during the duel. Even the victor in that scene is shown, though clearly as aggressive, as being very cautious of his actions.
Unfortunately, having both opponents remain in the zufechten for the majority of the fight (what commonly happens), isn't exactly sexy on screen in the same way a traditional theatrical fight is.
Actually, come to think of it, this is even more realistic looking than the set plays of people like Ringeck, Meyer, Fabris and others. In the plays and examples given in most manuals, you don't really get the image of BOTH combatants screwing up at the same time.
I guess it goes to show that what happens is often quite different than what is planned. I think that the Duellist shows that difference quite well, which is why most of us here who spar can sympathise with it.
Prepositions are not words to end sentences with.