Midway through Season 3, Anakin, Ahsoka, and Obi-Wan got new looks. Anakin and Obi-Wan look more like themselves in Episode III, Ahsoka is taller, she has a different outfit and has two lightsabers. It just happened, it first started in Season 3, Episode 10 Pursuit of Peace. It was posted online from a magazine a little while before the episode aired that they would have new looks. There were many online chats about it, many were excited. About the lightsabers, I saw a video on YouTube (A behind the scenes) where The Director said that Anakin gave Ahsoka a second lightsaber. Since she has a different fighting style, and is rather small she could block with her main blade and stab with the other.
It would be nice if we got into more detail about it, but I don't think we will. :(