"Kill Vance" is a mission objective in Queen of Pirates, King of Fools
Walkthrough[edit]
If you succeeded in a tree approach, you should have little trouble lining up the shot on him and Jing. A quick shot on him then on Jing and you are done.
If you had to approach from a different angle, then try to get some height or be sure that you have a number of pistols loaded. You will likely have a clean shot on Vance.