I get the impression that my shihan places much value in having a strong fighting spirit. I think that his not interrupting the conflict I described may have been the result of his desire for students to learn to develop this spirit. This is a guess, of course, but he has given me some reason to believe I might be right. For instance, he will try to "rattle" you during rank testing by telling your uke to give you a hard time or by abandoning the established test criteria completely for his own list of surprise techniques. Or he will lock or pin you right to the edge of your limit. Once he had me "test" a new shodan with yonkyo. The fellow was very slight and so my yonkyo on his wrists was very painful (I have thick wrists from powerlifting so his yonkyo didn't hurt at all). Seeing his discomfort I eased off for a time but my shihan saw this and scolded me for doing so. He then stood behind me and watched to make sure that I applied yonkyo full force for the approximately one hundred times we did it. On one hand, I felt very uncomfortable treating this guy this way, but, on the other, I recognized that this was what I had experienced many times from my shihan and that it was part of being a serious student under his instruction. He wasn't being mean, he was trying to toughen this new shodan and remind him that he was now, as a shodan, on a different level in terms of what was expected from him. His fighting spirit would have to grow to meet the challenges of being a yudansha. This spirit, I believe, is what my shihan was, perhaps, encouraging when he didn't interfere with the yonkyu and sandan who scuffled.
As I said, the conflict was short-lived and relatively contained. I'm sure if it had been wilder he would have intervened.
How do you who teach develop fighting spirit in your students? Is this even a concern?
Thanks for your comments on this!