I like to think of lightsabers not as highly specialized Jedi weapons, but simply as being outdated, like real swords. They were once used by every army, but when blasters and other ranged weapons emerged, they stopped being used and were more like ceremonial weapons. Jedi Knights kept using them out of tradition and because their enhanced reaction made them still effective against modern blasters.
I think Palpatine should rely entirely on the Force to fight his opponents. I also don’t see how Maul necessarily needs to be trained in lightsaber combat by Palpatine, that’s a skill he could have picked up anywhere else. Neither Obi-Wan nor Yoda are shown to teach Luke about lightsaber duel techniques.