In "Just Lather Thats All'', is it phisically easy for Torres to kill people, but mentaly hard?
Yes, that is correct. His thoughts were totally conflicted; he wanted to take revenge by killing Captain Torres, which had killed many friends. Then he reminded himself that revenge is not the only way to restore balance.
The reader understands the barber's conflict, but never the thoughts and feelings of Captain Torres. The barber feels proud of himself and takes much pride in his social position".. I am a good barber, the best in town..." He realises that he could not hurt himself which is what he would be doing if he killed the Captain. In one moment he would do something that would affect his life forever. If he killed the Captain he would be killed by the government. More importantly he realizes that if he killed the Captain he would not be able to live in peace with himself. He said: ."..It was going to be very difficult to explain that I had him right in my hands and let him go peacefully - alive and shaved."
In any case he did the right thing and just gave a good shave. It was mentally impossible for him to kill the Captain.