Shar is the first evil. *The* disagreement that started the divine battle was the creation of the sun. Selune made the sun at the request of Chantea. Shar attacked Selune at the slight and tried to blot out the sun. But that was then -- extinguishing the sun and all life that sprung from its creation is just the start. Once she was happy to maintain the balance between light and dark but now she wants to return everything to time before Selune existed -- when even Shar herself was simply "the void". She wants to bring an end to all things and the destruction of the weave is just one part of her secret agenda.
I don't know if Shar is the most evil but evil was her creation.
