But it also requires strength, and what is stronger? One blade being held with two hands, or one blade being held with 1 hand?
Yes but the permise is there besides you need to remember force users would use the force to augment their strengh, and atacks, so that means very litle, it depends on the user realy.
Look at malgus on the return trailer, hacking off TROWING debrie while dual wielding, those atacks seemed powerfull enough for instance.