Board Thread:Speculation House/@comment-27143816-20160225024520/@comment-24432027-20160303042134

JadenLan wrote: Your theory is that eye color is important in chosing a maiden, right?

Ozpin said that the rules are: last thoughts of a dying maide, has to be female and has to be fairly young.

He did not mention anything else. So either your theory is wrong, or Ozpin is a liar. And since the person giving important exposition should not be a liar as it would break the show the only other answer is that you are wrong. They only mentioned that's the two rules they know of...perhaps they are guidelines and they didn't know that the powers tended to fall in people with similar eye colors. But that was a recent development by RT.