I don't think there is any problems about the Kyuubi or Hachibi, we saw it turned much more powerful without the Kyuubi or Hachibi's chakra.You mean Jubi?
It's because it isn't complete because it doesn't have all the 8 and 9 tails chakra.
well that can be the jubis weakness they probably ganna aim for the other hand i think that maybe he's weak pointWho cares about a missing arm when j uubi is fodderizing the entire shinobi alliance:scorps: