Benicio del Toro's character, at the end, is facing the cartel boss and the guy refers to him as 'the conscientious lawyer', what he was when this began. You have to wonder at how long he trained, how many hours under first-class instructors, to learn to shoot and move as he does. And some of the other things he learned to do.
In one of the Matt Helm novels he observes that for every number of people you can intimidate or scare off, there will be one who'll come back with a knife or club or gun. The boss apparently didn't believe anyone not a cartel guy could be as ruthless as he was.
Boy, was he wrong.