see you auntie said:
Didn't Lucas originally imagine lightsabers or more importantly the weapon that a Jedi wields as requiring an immense amount of focus to use as they were supposedly made of a dense energy. Hence Jedi were the only ones who could weild them and why they often used a two handed grip, because they were heavy, and they'd use short precise strikes as not to waste energy fighting.

I don't even know if that make any sense (a dense energy?) but my memory of this is fuzzy. If anyone knows what the hell I'm talking about please add some input.

IN TPM there's a hint that the only-Jedis-can-use-them rule has gone. Because Qui Gon tells Anakin maybe his possession of a lightsaber doesn't mean he's a Jedi, maybe he just killed a Jedi and took it from them. Presumably a guy wouldn't be carrying around a weapon if he couldn't use it, so this sounds like a non-Jedi could use a lightsaber.