Creationists often pose the fallacious question, "what good is half a wing"?
Consider that many birds like chickens have wings that aren't that efficient for distance flying, yet still help them gain a little ground. ...And it's already been speculated that feathers could have served as ornamentation, especially for attracting mates.
But looking at a video of a rooster on the attack gave me some insight into how a Velociraptor might have used its feathers. A rooster uses its wings to provide lift while kicking with its claws:
...and the Velociraptor was built for slashing with its claws.
Illustrators often portray the Velociraptor as using its hands extended on the attack, but I wonder if a more accurate portrayal would be half-buoyed in the air in a rear-claws forward attack?