I'm wondering whether to let that knight just get cut in half in a spurt of "beautiful blood" or take an explosion to the knee a la priests, or make him actually tough.

Either way if someone doesn't back up Athinar, he's about to get pummeled. You realize that he ran straight into the square full of the knight and something like 20 or 30 priests and guards? They'll just dogpile him, but fortunately there's at least Torrens and Narza in the vicinity to help.