Just show up one point, since the anime put of legit canon stuff in the past and we learning more about ryou, more I think about Vista and Ashura, more I believe their epithet with "flower" isn´t just visual aspect but more clear a ability.
Vista at least use flower attack in anime, Ashura against Jack and with more we learning, with more I believe they not just use a visual "flower" attack, they really use some kinda of ryou attack:
Vista in anime
Ashura vs Jack:
And then the anime kinda show such stuff:
I believe more that this isn´t such visual aspect, I think Ashura use Ryou in that panel to cut though Jack sword and his strong durability, something with neither Inu or Neko couldn´t do with their sword. Jack didn´t expect it and cut together with his sword who was strong enough to block the sword attacks against Inu and Neko.
I think they use ryou and making it to multiple small particles and use it a cut ability similar like Byakuya from Bleach who use his Senbonzakura as bankai and attacking with really sharp flower(visual) attacks:
That is what Vista and Ashura did with their "flower" attack, it isn´t just visual they really spam such attack, I wouldn´t be surprise if Ashura can do something similar like Byakuya and attacking Kaido with it later in the battle. Probably Vista is really skilled in Ryou too, that is their epithet and it is insane how strong they became with alone ryou.
After this chapter I think every Scabbard has his own epithet/element:
Kinemon: Fire
Raizo: Wind
Kiku: Snow
Inu/Neko: Lightning
Kawamatsu: Water
Ashura: Flower Ryou
Denjiro: Ryou/Darkness/something similar like Ashura(?)
I think the epithet of Denjiro and Ashura come as the last, the strongest scabbard using their strongest attack before they get defeated by Kaido. Ashura has really a lethal swordmanskill, blocking ryou for character with no good haki/durability would end fatal and bad.