@Framing A Moose what are the bullets made of? Wouldn't shooting something evil with them make it more powerful?
They're just normal bullets, only enchanted with unholy power. As for their effect, I always viewed unholy power (and holy power for that matter) as a type of weapon. While it can be more effective on the ones who it was meant to harm (in this case celestial beings), it can also be turned around and used against those who usually wield it. But you're the GM, so it's your choice. Just remember that if you do choose to make it less useful against unholy creatures, when it comes times to go up against angels and such, Dusk will have the same problem.
@olcharlieboi
Could you give me a list of Dusk's abilities? Just so I can make their opposites? ^_^