the Jedi are all but wiped out in the Original Trilogy why would either need to carry a saber on them? The Emperor was well guarded and could use darkside powers on any would be opponent, his only real threat would have been Vader , and that was only once Luke's existence became known to them, although by that stage Palpatine's arrogance probably meant he had no reason to wield a saber.

Yoda , living in Exile on Dagobah , might have had some day to day practical uses for a saber, but I always pictured him as more of a monk like character living in peace with his surroundings and using his other senses to protect himself from predators, and besides, he was a puppet too so it would have been beyond limitations for him to wield a saber.