He can copy anything. That's it. If you re-read the Kaijo High – Seiren High Winter Cup match chapters, you will find that Kasamatsu said that Kise's Emperor's Eye is not completely perfect as Akashi's. Emperor's Eye main ability is to detect even smallest movement. Maybe Kise trained his eyes to work like Akashi's (all Generation of Miracles' talents are copied by Kise by hard trainings to make his body able to copy those uncopitable talents).