Well, I think is pretty clear what I wrote: we need a better translation.
But, again, if it is confirmed, we'll just have to end this denial issue
So I thought about this all morning. Kaido's line is essentially "this nature of this Haki is..."
And it has probably been conflated with Kaido subsequently acknowledgment, "that is Oden's katana?!"
What was weird to me was that earlier Kaido mentioned Oden's Ryuo when talking about the Scabbards. Due to misconception and a lazy sort of convenience, people are using the misspelling "Ryou" to describe the advanced Haki that doesn't have an official name, but Ryuo is merely the name of armament Haki in Wano. Just like mantra was literally just observation. Characters either use one word or the other... except Kaido said Ryuo despite being a foreigner. Maybe Oda forgot that he says Ryuo, maybe there's the fact that he obviously would have learned about Haki before reaching Wano.
So my own conclusion is that he says Ryuo to describe the Haki of a Wano native, and he says Haki here because he's not actually talking about a Wano native. In any case it's very vague but I certainly wouldn't come away thinking he's talking about Oden there. I'd more easily believe it's the dragon aura, the weird way Enma is being imbued BY ZORO, or the combination of both