because really, it was so improbable that Benwick and Louisa should fall in love, their characters being so different (the reference to "spirit and gentleness being incompatible") that everyone who knew them was surprised by it and talking of it. I don't believe Anne was comparing the two men or at all sad on her own account by the news of Benwick's engagement.

But that curious reference to manners again! Second time in the novel that CW's manners are described as better or superior to anyone elses. Upon meeting Harville for the first time in ch. 9 we are told "Captain Harville, though not equalling CW in manners..."

Could manners also imply character or personality? Why else would Adm Croft refer to CW's manners when Anne just spoke of Benwick's excellent character.

Why would one person's manners be more to your taste than someone else's? Unless it means that how things are said, how honest one is while being polite, and the words one chooses (and how many of them) reflects a person's character and not just his manners.