Cut the cope.... Oda just doesn't emphasize coloring Zoro's swords all the time when he's clashing.
"No hardening in the middle two panels, but Zoro finally kicks it up a notch in the bottom panel when he's falling, and hardens his Swords.'
But wait! There's more....
Here you see Zoro clashing with King's Swords while using hardening, but then magically decides to turn it off afterwards.
Holy shit! Here he have Zoro going from not hardened, to hardened, to not hardened in the span of three panels!
Am I doing this right?
I can find countless other panels of Oda's inconsistency of coloring Zoro's Swords when he is using hardened. Hell, go read chapter 1032 if you really want to have your mind blown on how inconsistent Oda is on coloring hardened Swords.
A lot of the time Oda doesn't fully color Zoro's swords black when he's in the midst of clashes. You'll see whitespace, with black lines, which is exactly what we are getting in the Lucci vs Zoro panel.
Zoro didn't go from using hardening on base Lucci, to not using it on awakened Lucci. The smoke on the end of Zoro's sword alone is enough to tell you he is using hardening, because that is a byproduct of when Zoro overflows his haki.