I just did this last weekend. I travel light and typically don't check luggage. On the way down from San Jose I carried on my overnight bag and knapsack. When you purchase a lightsaber you're given a carrying case that fits both the lightsaber and the blade. At the time I was worried about getting the saber's grip through TSA so I removed the lightsaber from the blade, put the lightsaber in my bag, and checked it. I then carried my knapsack and the blade in its case onto the plane. Although it sounds like TSA is okay carrying both the saber and the blade, one benefit of separating the two is that it reduces the length. This could be useful if overhead space is tight.
It took me a couple of minutes to figure out how to remove the blade. To do this, take the blade in one hand and the saber/emitter in the other. Push the blade down towards the grip and, while holding it down, turn it about one quarter turn. The blade will release and slide out easily. There is actually a sound effect associated with doing this, which I thought was a cool touch.
If you buy a lightsaber consider purchasing an additional kiber crystal for it. In retrospect I was I had done this. I think they are available from Dok Ondar's store.
