I am from India and in our country, the law enforcement department (Police Department) starts the new recruits with same training. But later on based on the recruits inclinations and skills, they are diverted towards other departments like Cyber Crime, Narcotics, Special Forces and so on. I don't know how things work in USA, but Hank from Breaking Bad must have not just entered DEA directly. He must have worked his way through APD and then got promoted to DEA as he must have obtained extensive knowledge of drugs.
My point here is, Hank being a law enforcement officer, he has been trained to fight criminals and even kill them if necessary. Also, this whole thing is part of his job. So knowing all this fact, why did Hank Schrader got disturbed after killing Tuco. Also, in El Paso, when the team he is working with gets blown up. He again gets scared.
I mean, every cop, soldier or person involved in defense service know what he is signing up for. I don't understand Hank's character because of this incidents.