Board Thread:Speculation House/@comment-35757751-20180602170102/@comment-36105773-20180707053408

It's safe to conclude that the SE powers target both Maidens and Grimm parts. After the Fall of Beacon, Salem told Cinder that it was because of her maiden powers that she was affected by Ruby's SE powers. Cinder also did not have any Grimm parts at that time. If you argue that the Grimm bug still existed on Cinder's back, only her back would have been affected, just as only her arm was affected at Haven. Then, Ruby's 2nd SE powers visibly caused pain to Cinder's Grimm arm during the battle at Haven. I still believe that Ruby's 2nd SE powers at Haven were weaker and didn't reach their full extent because Emerald knocked Ruby out.

I have theory that might explain why the SE powers target both Maiden powers and Grimm parts. Perhaps the Silver-Eyed Warriors were created by or are descended in some way from the gods of light and darkness to control and limit Ozpin and Salem. Ozpin, who was probably the wizard in the story, created the Maidens and Maiden Powers. Salem is the master and creator of the Grimm. Silver eyes could conteract both of them to serve as a check in case one of them became too powerful. Of course, this is only a theory.

We will probably find out the answer eventually as the anime progresses, hopefully in Volume 6.