"At most only three ken?"
Harano, using the spear-handling technique he'd studied during his last "training," held a spear three and a half ken long. First he tried the mid-level upright stance, then shifted to a bow stance and raised the spear from the rear. Sure enough, he felt his weight pitch forward uncomfortably, his footing unsteady. Apparently, Oda Nobunaga wasn't just making stuff up. Once a spear gets past three ken in length, it's really awkward to use. No wonder Nobunaga didn't keep lengthening his spears.
This matter was in Ah Qing's hands; she took the experimental long spear from Harano, nodded slightly, and said, "Best to set the length at three ken. Three-and-a-half is too much for some people—they've not performed well these past few days."