TheBoost said:
Making purple a sign of rank would seem confusing. A whole lot of the Jedi action we see are indeed masters on the council, so purple would not stand out that much. Also, would Obi get a purple blade when he achieves that rank?

Why would it seem confusing? If anything, it eliminates the confusion as to why a purple lightsaber even exists.

Things tend to be less confusing when they have a known purpose. Think of it like the karate color belt system. Yellow belts, green belts, black belts... It's the same concept, earned for the level of mastery they've achieved. Think of how the purple stands out in a shot like the Geonosian arena during the charge, or the subsequent battle where there are many Jedi on the battlefield.

And no, Obi-Wan wouldn't have one because (it seemed to me anyway) he was just "filling in" on the council during wartime. And of course Anakin wouldn't get one because they don't grant him the rank of Master.

Then again, not every master is on the council either. Look at Qui-Gon. So, maybe it's reserved for only the top official council members only. Who knows? You could come up with any explanation you want to. Anything would be better than having only one as it is now.