He was certainly not talking about being less refined at sword techniques though. The skill he was talking about in this particular instance is reactions. Getting injured in a fight isn't a swordsman-specific thing. And it's not like I am saying skills don't matter for swordsmen. Obviously, skills matter to any given fighter with any given fighting style.
What I am asking is, since you seem to imply being refined(whatever that means) is what makes you a better swordsman as opposed to just being overall stronger, what aspect about Zoro became so drastically more refined after 1009 or 1036 that he's now being called a master swordsman?
That's how martial arts works. The more refined your techniques are, the more effective they become. Zoro doesn't have to create new attacks, he just needs to refine his Swordsmanship so his already established attacks become stronger. That's why Zoro was in awe at this man who had the most subtle Swordsmanship he'd ever seen. The same man who said that without subtlety, you might as well be swinging an iron bar. The same man who sits at the very Top of the Swordsman World. But for some reason, we shouldn't take HIS word on it.
From 1009 to 1036, Zoro seems to have managed to tame Enma completely, which is something that only one of the best Swordsmen who ever lived, managed to do. I'd say that's more grounds for his Rank to increase, over "He now has AdCoC" or "His skills have become more refined." But then again, it could have been a combination of multiple things that raised Zoro's rank. It's kind of hard to tell.
But until you guys can convince me that Vista is some kind of Haki God, or offer a valid explanation as to why he shares the same Sword rank as Mihawk, while not being a Haki god, outside of his Swordsmanship is just that damn good, I am not buying for a second that Zoro's Sword rank increased just because he gained AdCoC.