It was stated in an earlier chapter that it's only considered cannibalism when it's the same exactly species like a pixie dragon eating another pixie dragon but an earth/red/whatever else dragon is fair game
Oh yeah, she's either going to have the same fate as Hughes in Fullmetal Alchemist (learning a massive secret but dies before telling the group) or she gets captured and a rescue mission is needed. Hopefully it's just a capture situation and not a funeral.
@Shiromon wasn't Ragna in the future able to kill all the dragons but at the cost of his life? So this isn't much of a limit break but reaching his true potential, right?