I know I’m probably preaching to the choir here, but of all the prequels’ many failings, this is perhaps the most baffling. It directly contradicts the OT on multiple levels. Yoda is established as a wise sage for whom “size matters not” who believes “wars not make one great” and claims “a Jedi uses the force for knowledge and defense, never for attack.” Yet in the prequels he flips around all over the place with a lightsaber and has no qualms about charging into battle with it.
But for Palpatine it’s even more baffling. While you could make a (flimsy) case that it’s technically never directly contradicted that Yoda might have at one time used a lightsaber, which is true despite it being thematically obvious that Yoda should not use one, you can’t for Palpatine. The guy treats Luke’s saber with snide scorn, condescendingly referring to it as a “Jedi weapon” and says it is “much like your father’s.” Implying the only reason Vader even had a lightsaber is because he used to be a Jedi, and the Sith otherwise don’t bother with them.
So why the hell do we not only see these two characters fight with lightsabers in the prequels, we even see them fight each other? That might make that sequence the most ridiculous scene in the entire saga. It simply never should have happened.