The smoke is his swords pulling excess armament zoro can normally let put himself but its still being done because of enma's power/ability being used throughout all zoros swords
Umm no you missed the context.
When Zoro first pulled Enma, Enma forcefully pulled out excessive Ryou out of him hence why Zoro said "Give it back"
Since then Zoro has been regulating his Haki preventing Enma from forcefully pulling out too much and when smoke comes out he himself willingly gives Enma excessive Haki.
Then when Zoro was on the floor, Zoro got weaker, Enma once again excessively pulled Haki.
Then Zoro was like "Alright fuck it, I'll just give Enma and all my swords all my Haki" he did that willingly, and doing so made Zoro coat swords with CoC since Zoro had CoC in him as well.
Giving all his Haki into swords include CoC.
Enma has no such ability to impact other swords lol