Most of the psychopaths you encounter will have a fighting pattern and will take small breaks.

In order to kill them quickly, you should either get a Light Sword (gems and flashlight) or Knife Gloves (bowie knife and boxing gloves).

You should also have a Beer Hat just in case. When they take a small break, slash them up to 4 times and quickly run away.

Repeat this until they are dead.

Some psychopaths don't take breaks!