It doesn't make any difference. Ragnos doesn't have to know everything they know to be leagues ahead of them in power.
Oh, it does make a difference. By admitting that Ragnos doesn't know everything that his inferior (Sadow) does, you can't say that powers that Sadow possesses belongs to Ragnos. So the old excuse of: "Sadow could make stars go supernova - so Ragnos obviously has to be the PWNZOrs!" no longer applies, because Ragnos hasn't been proven to possess that power, that expertise with Sith Alchemy or technology.
When was Sidious said to be the most knowledgeable Sith Lord in reguards to lightsaber combat? Sidious was still learning a lot of things after Darth Maul died, he wasn't the most knowledgeable at that time necessarily. And why would Sidious use Juyo? It doesn't fit his body type or fighting style at all. Sidious didn't know everything on the holocrons in his posession.
Sidious = most Sith knowledge, period. Since Sith knowledge can mean Force powers and saber knowledge, it is "logical" to deduce that Palpatine possessed considerable knowledge of Jedi/Sith fighting forms.
I'm not impressed with your argument, Glentract. You said that Maul learned his fighting form from a holocron. That would mean that the holocron belonged to Sidious. Considering what we know about Sidious - and his thirst for knowledge - it's rather inept of you to try to say that he didn't know it as well.