I really like Nyriss, but I don't think she wins. Saber wise she probably takes a victory though not by much. We saw Vaylin take on her mother on equal footing, not a small feat. Senya is (iirc) a very highly skilled duelist, who (again, iirc) was the strongest Knight of Zakuul; this being what drew Valkorion to her. None the less Nyriss takes sabers but definitely loses the others. Reason being Senya said that Vaylin literally began moving small objects from INSIDE THE WOMB BEFORE SHE WAS EVEN BORN. I don't think Nyriss can compete with that.