As seen, it wasn't swordsmanship that was key to victory. It was more or less a mastery of the Force in balance, that defeats Palpatine. Palpatine, who had been using the Dark Side to cloud the vision of the Jedi for a long time, finally has the Light Side cloud his vision at the end, when it comes to Luke Skywalker, and what was left of Anakin Skywalker. Palpatine, great foreseer of all thing, didn't sense Luke Skywalker had come to Endor, but Vader had. Palpatine's view of how things were playing out were likely as clouded as the Jedi's had been during the time of the Clone Wars.
For swordsmanship, Palpatine didn't like using his lightsabers, it was probably beneath him. However, sometimes he's do it for fun, like when he used both sabers to take on the two Night Brothers on Mandalore. He was having fun there. In his office, when Windu entered, Palpatine decided to have some fun again, slaughtering three Jedi Masters in about a minute. Windu's combat style seems to be the only reason he remained to fight Palpatine. Be it that he was having his Dark Side powers channeled back to himself by Windu, or if he was stalling for Anakin to come so he could finish the corruption....that is still debated.