Although she isn't an "official" editor, after Tabby read Bag of Bones, Steve deleted an entire section he'd written about what Mike Noonan was doing after Jo died. He explained to Tabby that he thought readers might want to know what Mike had been doing and Tabby's response was that "(he) didn't need to bore them to death doing it." That's one example of how it took someone else to point out a section that Steve might have thought was good but others might not.
Thanks, but you already told that one time.
I think to quite a lot of writers their wife/husband is their most important sounding board.
I remember though when reading The Waste Lands (a long, long time ago) that I felt towards the end the prose got 'messier'. That may have been one of the cases where an editor might have helped. It's too long ago to give details though, just my feeling at the time when I was reading it. For me it's often hard to say if that was the original writing or just the translator of course.
But on the whole I don't find them any different from the majority of his books that was edited.