The physical and mental strain is building rapidly. Kiysa has seen less and less of the world around them the longer this fight has went on. Now the entire world is gone, a black haze that only contains herself and Duncan. She has become blind to the burning in her lungs and the numbness in her arms and legs. Powered purely on adrenaline and her indomitable spirit. One final thrust she dodges by the slimmest margin, but she sees his hands clench and the muscles in his arms bulge. This thrust will change to become a horizontal swing. In an instant she sees her winning move. She has to instigate a clash. From there she can win. She will win!
Power Duncan has not experienced strikes his blade as Kiysa twists with new vigor and parries his strike, knocking it aside as she goes to cut him down with the same flow. With great power and determination Duncan does the same, bringing his blade back and stopping her return fire. Over and over they trade, standing their ground as they both sense the end. Kiysa's spirit has evolved, refining itself for one final explosive push, burning everything as if there will not be another day. Duncan can feel it, each attack she throws has an intensity even beyond where he is now, forced to block most of them now as they have become dangerous to attempt to parry. But he has to keep up the assault. They both were searching for the same thing. And when both Kiysa and Duncan sense that the other is just a hair out of place, they knew it was time.
Their blades clash. They grind together with one final burst of strength. Still, Duncan is physically stronger. His victory condition is met.
Which meant Kiysa's victory is guaranteed.
With Duncan's focus on the clash, he does not see through Ideal Girl. Duncan met Kiysa's blade in a way where he can still brace to have a hand free to grab Kiysa's arm with his left hand. The shock on Kiysa's face almost hides something from him. And it is from the periphery of his left eye that he senses it. Defeat.