Sure, I never said otherwise. Still, the fact that Keisha made such an impression on Riboku that he thought that much about him is extremely impressive.
Naturally, Kei Sha was elite. His talent was undeniable, and no one knew that better than Ri Boku, who practically raised him.
The guy was closest to becoming a Three Great Heaven. It annoys me how little emphasis Hara put on that. By now, Shin and the HSA have killed 12 Zhao generals - 8 or 9 were slain by Shin personally. They should revile him like the second coming of Ou Ki.
Duke Hyou smelled the hint of a trap, true. But he still did what he thought was best. And fell for what Keisha had prepared. There's no indication whatsoever that a "narrative purpose" made him do things differently.
If anything, Hara made Keisha a general of such a lv where he could effectively utilize that to make Shin's awakened instictual prowess shine (through the bad situation Keisha had createad).
Duke Hyou didn't smell a hint of a trap. He
knew there was a trap. He jumped in regardless for the same reason Kan Ki pressed on to Gian, knowing they would likely fall into a trap.
The narrative purpose is clear both for Duke Hyou at Kankoku Pass and Kan Ki at Gian: this is who these men are. The decision to press ahead anyway is informed by all the same thoughts, impulses as instincts that make them who they are. If it helps to understand what Kan Ki is thinking of, just think back to when Ou Hon pulled that insane reversal at Shukai Plain and essentially crippled the Ba Nan Ji Army.
Duke Hyou was the quintessential Instinctual Type, and not only that, but he also had more experience than just about anyone. Triggering Kei Sha's trap was a decision based on confidence. One that looked like it was misjudged, but we'll never know because Shin had his moment - which is clearly what the narrative was serving.
Whether in antiquity or modern times, how likely do you think it is a military commander will anticipate a trap and willingly spring it? It must happen from time to time, be it hubris, confidence, incompetence, ignorance or any combination of the four. Soldiers themselves are valuable assets. No sensible commander is going to want to squander lives and trigger traps just to see what happens or what they could make of it in the chaos. Especially not an era where they are conditioned from birth that anyone and everyone, including high ranking generals and royalty, can be executed for failing in their duty.