Was mace more powerful than Sidious because he deflected Sidious's lightning back at him deforming his face?
Nope, Sidious fried him then pushed him out of the window with ease. He even laughed while doing it yelling he had unlimited power while the moment before that playing weak. He wasn't even going full blast on mace, Nyriss went for a killing blow immediatly and look how that turned out.. :P
Mace didnt kill Sidious or did we watch 2 different movies?
Revan killed Nyriss with a killing blow she ment for him and was put back at her . Thats skill and his ability to resist it and do such a rare feet is power .
Mace blocked lightning with his lightsaber which is sorta rare I guess but no where as rare as someone doing it with his hand and killing the person who shot lightning at him .
Also Sidious was playing with Mace , Nyriss wasn't playing with Revan .