Jerkass Woobie: Vita, before meeting Hayate, was a jerk even to the other Wolkenritter as shown in the sound stages, and harshly rebuffed Reinforce's efforts to reach out to her. She who also the one who seemed to suffer the most from a life of constant fighting.
They Wasted a Perfectly Good Plot: We never find out how Hayate reacted to hearing about Graham having planned to use her to seal away the Book of Darkness, or if she ever found out at all.
Kyouya and Miyuki are shown to be expert swordsmen in Triangle Heart 3 ~sweet songs forever~. One of the enemies their sister is fighting in A's is a sword master. Despite the obvious opportunity for a duel between Signum and either non-magical Takamachi sibling, the most significant event featuring those two in that season is Miyuki ribbing Kyouya about his love life.
Considering how much Vita prides herself on there being nothing in the world she cannot break, why didn't she ever seek out a rematch with Yuuno Scrya, the boy who — without any Device and lacking her centuries of combat experience — managed to fend her off entirely without even giving her the dignity of his full attention? There's no way that he wouldn't have infuriated her, and no way she would have forgotten or forgiven the offense to her pride. At the very least, she should have become the SECOND antagonistically snarky bane in his life, after Chrono.
On the other hand, Vita wasn't even using her full power against Yuuno, as she had to conserve her cartridges (she isn't using the Rocket Form that shattered Nanoha's shields). She did, however, manage to prevent him from casting the teleportation spell that would have enabled them to escape, forcing Nanoha to use Starlight Breaker to destroy the barrier and force the Wolkenritter to retreat.