Vampires have super reflexes. They can react way faster than humans. They react faster than most things. When they move, you don't even see them move. All you see is a blur.
This is an advantage for when they are fighting humans because the humans wouldn't see them move and the humans would be beaten very easily. But a vampire using their super reflexes against a vampire isn't a good idea since the other vampires would know since they have the same strenghts and reflexes.