A finger on the trigger. That is what decides if you are safe. And that finger the ambassador was looking at? Was on the trigger. And that finger belonged to none other than Dead Eye. The Assassin Among Assassins.
And this ambassador? He has done some pretty bad things to end up in Dead Eye's bingo book of enemies.
First he murdered Dead Eye's wife. Which earned him a death in the first place. He also took control of the entire area with his inherited wealth. Which Dead Eye couldn't care for, but that was his job. To be the best hired gun with the best eye.