Pyrite is a good stone if you want to increase your self-confidence. It reduces stress and frustrations. It is a good stone for when you worry too much. Pyrite is a grounding stone that can give you a lot of self-insight. It makes you open and honest and gives you the strength to break through patterns. It helps you to get to the bottom of a problem and solve it.
It's best to keep pyrite away from water, as it can rust because of the iron it contains. With that in mind, it can be cleansed and charged in every other way. Here I explain more about cleansing and here about charging crystals. :)