I’m pretty sure green smoke is ryuo, since we saw Enma constantly smoking whenever Zoro was using it in Wano. I think when Zoro “tamed” Enma he learned to give that same haki output to his other swords, and then that in tandem with CoC coating is what constitutes KoH
Still, that one panel of Zoro vs. Lucci with the smoking swords doesn’t really make sense considering every Zoro vs. Lucci panel afterwards was with 2 swords and no smoke
In general, I don’t really think Oda gave much thought to this fight nor to haki overall. So many inconsistencies, all to be exploited for the sake of agenda (myself included) lmao