He didn't want to repeat the same scenario that happened a moment ago where Yi would continue to attack, allowing him to only defend. Xuefeng wanted to end it swiftly, without prolonging it too much, so he didn't aim for that strategy.
Lunging forward he decided to thrust towards the open space around her waist, where her hands were holding the hilt of the sword. First, it would be hard to block and parry such an attack, but it was also his tactic to confuse her.
It's because this attack is too easy to counter with different methods like dodging to the side and cutting towards his open body. He wanted to bait her into thinking that he left an opening before striking her unsuspectedly.
He executed his plan just as he imagined. Diving with his sword towards Yi's waist, he pretended to shift the balance into his front leg which would not allow him to fall back if necessary and successfully baited Yi into stepping in his trap.
