Vayu immediately knew that his student wants to sacrifice himself for the win. They needed to get enough time for Vayu to destroy the Golden Sprite but even he admits that it is no easy feat. The Golden Sprite even evaded his sword slashes with the way that is familiar to him.
He suddenly remembered that the way that the Golden Sprite evaded is almost the same pattern as Sirius. The Golden Sprite did not just dodge but always dodged at the last minute like what Sirius usually does. He knows this because he managed to spar with Sirius before to see if he could land a hit.
The Golden Sprite has a sharp instinct when it comes to danger. The only way to destroy it would be to either set a trap for it or out speed its instincts. If the developers knew what Vayu is thinking, then they would praise him as the Golden Sprite is actually loaded with Sirius' data when it comes to avoiding attacks.