Draco simply raised a finger and fired out another wind bullet. When it struck his foe, it actually didn't knock him out, and a stronger rebound rushed back at Draco with twice the power and speed.
He flicked it aside and let it crash into a part of the stadium that was not occupied by people, where the seats and wall were blasted open with ease. Many faces changed when they saw this, as many had secretly disdained the girl from before for passing out and foaming due to a 'mere' wind bullet, but seeing the kind of damage it had caused humbled them greatly.
The lad who resisted it himself spat out a clod of blood, showing that his defense wasn't perfect... neither was his rebound. To be able to perfectly rebound, you had to be able to perfectly defend.