It can only be passed down to the opposite sex. It can only be told to three people, with the third person gaining the power. The person performing it does not need to believe in it fully or be sinless since the blood verse is so powerful.
This ability can only be passed down to individuals of the opposite sex. It can only be shared with three people, and the third person gains power from this transmission. The individual performing the act does not need to believe in it or be morally perfect because the blood verse is incredibly potent.