A long while ago (5-10 years) I read a science fiction novel in which characters dueled with nanotechnology blades that are Sharpened to a Single Atom.
One aspect I found interesting was that the blades in this story would not cut through other blades that used the same technology, but instead would violently bounce off from them. This meant that in a duel, you were far more likely to be injured by your own blade rebounding than than by your opponent's. In the story, they paraphrased this as something like "your opponent's blade is your weapon, your own blade is his weapon."
I've read through the TV Tropes page linked above, and there are obviously a lot of stories with absurdly sharp blades. But none of them mention the "bouncing off" aspect, so I can't be sure they are the one I'm looking for.
The only other things I can remember are that these blades were held together by a force field. And one of the important duels may have taken place in a body of shallow water, perhaps on an ocean world.
