Meditate to clear your mind. Begin to focus on your energy/chi/whatever you choose to call it.
Feel its flow, begin to direct it in different parts of your person.
Put your hands together in front of you, and move your energy through your hands. You can choose and change the direction as you like. Move on when you feel confident.
Hold your hands near each other, but not touching. Feel your energy flowing between your hands. Direct it to build up there. A sphere is an easy form to imagine it. That is a psi ball.
An aura sword would basically be no different; directing your energy into the shape of a sword. Some people practice with many shapes and forms.
It is part of energy manipulation, and useful in some works depending on how you do things.
If you are hoping this is something you will physically see or fee, or can physically effect anything in a direct manner, I hate to burst your bubble, but it is just energy and visualization.
But areas where this practice may help are with thoughtforms if you choose that direction, and directing your ethereal energy into spells.