The Elements of Harmony aren’t weapons. This is a basic fact, they are an extension of the Tree of Harmony a being that thinks for itself. A weapon is a mindless tool of destruction, there is no Harmony in destruction. A thousand years ago the two Royal Sisters fought. Nightmare Moon was a problem the Tree, nor Celestia saw coming. So at that moment when Celestia used the elements the tree guided the power to act the only way it could think of at that moment. Give the Tree of Harmony time to come up with a solution. A plan was formed and the Elements rested to build up the magic needed to save Luna, and Nightmare Moon. A thousand years later the time came to set the plan in motion...