So what is a Cruxim?

As I was searching through mythological creatures, I read about Kresniks, which are creatures from Croatian mythology and sometimes called Cruxim, or Dark Angels. They dine on vampires I decided to explore making my hero that: an angelic being whose mission was to kill vampires, because how can you be considered holy and yet spend your life killing others? And then I wondered, what if someone dear to him became a vampire? How would he handle that when his mission is to kill them all? 

In mythology, they often have black or blood-tipped wings and they might be able to "warg' into wolves. Read more about Cruxim here.