Despite fighting close to each other and without the use of any special means other than the Black Steel Spears they grasped tightly, the fighting efficiency and final results of their fights were completely different.
Jennie may not possess the worst stats but she was certainly the weakest in Liam's group. Her fighting proficiency was barely nonexistent. It was already a wonder that she was still alive. That was probably the only advantageous result of her fights. Jennie could survive and kill the Ordinary Shedim that would kill her otherwise, but that was already it.
Kian was different in that regard. He could ignore the ghastly looking monsters by considering the Shedim as his money-making tools. This enabled him to get over his unease and attack them with fast and smooth movements. With his Soultriat activated, he could defeat an Ordinary Shedim every two or three seconds. He was truly fast, which couldn't be underestimated, not even by Liam.