For this reason, I suggest activating Riposte or Duelist, not both. With both active, Riposte will never trigger, because Duelist will always consume your Reaction first.
I tested more carefully and now I can say that in the game you can activate both the Duelist and the Riposte and you get +2AC first than if enemy misses you can Riposte.
The reason why it did not work for me before is that there's no information that Duelist only work if you are wielding a Finess weapon (I should have guessed seeing the Duelist word )))
