Obiwan's lightsaber is blue. This is a well-known fact to fans of the Star Wars franchise, as Obiwan is portrayed using a blue lightsaber in the movies. The color of a Jedi's lightsaber is often associated with their affiliation and role within the Jedi Order, and blue lightsabers are typically used by Jedi Knights. Therefore, it can be inferred that Obiwan, being a Jedi Knight, would have a blue lightsaber.