Amon threw his poison knife.
Since his black core was very weak, he could only execute the beginner mastery of his Hundred Shooting Stars. The power it produced allowed him to only throw one knife and it could only travel a very limited distance. Luckily, Wei Sui was extremely close to him, so distance was not a problem.
The entire sequence happened in a blink of an eye. The poison knife flew from Amon's hand even before Amon's body fell to the ground.
Amon targeted the knife at Wei Sui's left foot. Wei Sui's claw art allowed her hand to be as hard as steel. Even at his peak, Amon's poison knife won't be able to penetrate her arm's skin. Her other body, however, was not so. Wei Sui's left arm was already crippled due to the wound on her shoulder, she could only move her right arm. That's why Amon targeted her left foot, which was her body part furthest from her right arm.
