Man kills burglar with sharp sword - defense of your home is perfectly legal

There are certain cases where being able to kill somebody else can be defended in court; one case is when you are killing in self-defense, another case is when, in the United States, you encounter a robber in your home, and in the course of defending your home, you kill the intruder.
Imagine a case when a person intrudes into a house, especially a house where there have been things stolen, and then finds himself encountering a sword wielding resident of the house who is ready to confront you.
In this case, the resident of the house used the sword to deadly effect, killing the intruder. The police normally have trouble arresting the residents involved in such incidents, since a person has the right to defend his home. (link to article):

Baltimore homicide detectives don’t believe a Johns Hopkins University student had “the intent to kill” when he used a samurai sword to confront an intruder behind his home, a police spokesman said Thursday. John Pontolillo, 20, a junior chemistry major from New Jersey, killed the man with a single blow early Tuesday after police said the suspected burglar lunged at him.
Pontolillo has not been charged in the death of Donald D. Rice, 49, who had a long rap sheet of burglary arrests and was released from jail just two days before the altercation. Prosecutors will determine whether charges are appropriate after consulting with police, a process that could take weeks.

Treating a bank robber with kindness

This is a new tactic about how to deal with bank robbers. Till now the established method of dealing with bank robbers has been to treat them gingerly, not confronting them, and to take measures that essentially deal with trying to catch the robber later. This would include either activating an alarm and/or dropping an exploding dye into the cash bag.
Now, there is a new element dropped in these measures. This measure is excessive friendliness. The premise is that an overdose of courtesy will unnerve would-be robbers and get them to rethink the crime. This is part of the 'Safecatch' system created by an FBI Special Agent and being adopted by banks in the Washington area. The concept is that a normal customer thinks friendliness and courtesy is great; but a robber really gets scared and does not understand the reasons for the same.
As an example, in a bank, when a robber walked in, the manager greeted him, and guided the robber to an equally friendly teller. This must have worked, for the robber asked for a roll of quarters and left.