One of the many lovely things about a perfect heart is that : it is a storage location of Divine mysteries and  secrets of God: What makes very a simple thing become absolutely powerful is the mystery attached to it.  
God takes a simple man or a simple thing that is least valued and turns it into a powerful weapon against the enemy but conceals the secret behind its operations in the Heart. And as long as that heart is perfect towards God, such secrets will remain a mystery to satan and his host. 
Desire a heart perfect towards God! For blessed are the pure in heart for they shall see God.