Searching the compiled subtitles, the term "bijae" (in the WITH2 subtitles it's "beejae") has come up before now, as a reference to challenges between units. I should have recognized it; my mistake.
But as of this episode we don't in fact know that any bijae--or any duels between individuals--will in fact happen. (In fact, in the only non-trivial mention so far, in Episode 9, a "jinsong beejae" was first set up and then cancelled.) So let's keep it that way until they do or do not happen.
P.S. The Episode 9 thing was that incident with the DFers being accused of soiling another unit's flag. They got bailed out because Baekje attacked and everybody had to go to war. But we never did find out who the culprit was.
Hey, that's right! I forgot about that! I seem to remember that Deokman was thought to have done it, but she was visiting with her sister-prin, but they didn't know they were sisters yet, and there was an implication that someone like Sukboom might have done it.
From Dae Jang-geum: Sun-dol: "Are you trying to dry me up and kill me? Why do you say the same things over and over every day? Rather, come and hit me once! Aigu!" But then: Dr. Lazarus: "By Grabthar's hammer, by the suns of Warvan... You shall be avenged."
Yeah, it wasn’t nearly as bad as the who-poisoned-Dae Joyoung fiasco, just because the sudden war gave them a reason to put it aside...but they really did just let it die. Unless they revisit it later on. One good thing, the series does go back and clear up loose ends sometimes. Not often enough, but sometimes. So we'll see.