Placing Amy at 13 indicates that the comic was aimed at girls in their early teens, so the level of violence depicted is not out of line with other fantasy materials aimed at tweens/teens. I thought that it actually treated the readers with respect in that it showed Dark Opal's evil in a primal way (the killing of one's own child) whereas many others would have had him resting on his evil laurels or trying to do something evil and failing utterly.