Welf and Mikoto manage to successfully stall Gareth with a last-minute assist from Tsubaki, ordered by Hephaistos to assist Hestia Familia. Wiene manages to give Tiona the slip, but the chase continues. In the process, the Amazoness witnesses Wiene save a demi child from a crumbling bridge.
When she corners her again, Tiona can’t go through with killing her, and lets her go, now sensing what it is Argonaut-kun saw in her, and acknowledging she’s more than just another monster.
Wiene reunites with Bell and Haruhime, but it’s not long before they’re confronted by Bete. Again asserting her newfound confidence and strength, Haruhime stalls Bete to allow the others to flee, then uses Uchide no Kozuchi to summon a leveled-up Aisha.
Haruhime may not be that good in an offensive battle, but those who love her like Aisha consider her battles to be their battles, and gladly fight in her place. Even though Aisha loses and doesn’t feel particularly cool about it, the fact is, she is extremely cool, while Bete’s just a hotheaded dork.
That brings us to the titular Decisive Battle, in which Bell and Ais dance once more, only this time with blades instead of eveningwear. As Finn expected, Ais isn’t prepared to make any distinction between Wiene and Monsters Who Make People Cry based on what she’s seen. Wiene went berserk before, she could do so again, and she can’t allow it.
That said, she is surprised that Bell is able to hold his own in their initial scuffle, such that she dispenses with holding back for the sake of their unique bond, and takes things up a notch. Bell can’t keep up, so he spams Firebolt at the stone arch above them and uses the debris cloud as cover to escape.
Finding the barred gate to a secret passage where he once stood up for Hestia, Bell has Wiene go through to meet up with the other Xenos, promising he’ll be right behind her. Round 2 with Ais commences, and Ais is not playing around. Her only accomodation to Bell is to warn him that she is going to cut him and it will hurt, a lot.
If she were to spill Bell’s blood, I doubt things would ever be the same between them—maybe they won’t be anyway—but thankfully Wiene sensed Bell was only lying to protect her (again) and comes back to put herself between Ais and Bell. Ais is shocked to hear her speak and express emotion—specifically concern for Bell.
It’s an inconvenient truth she’d rather not deal with. Things were easier when she thought Wiene was just a monster; now it will hurt her to kill her, but she’ll still kill her, because she has “deadly claws” and a “terrifying wing”. Wiene responds to that by literally tearing off the monstrous parts of her (not her jewel, that would kill her).
Wiene tearfully assures Ais that she ever loses herself again she’ll disappear “like she’s supposed to”, but she doesn’t want to go back to being in the “pitch black”. Bell saved her, and she wants to stay with him. Having witnessed Wiene act not like a monster at all, Ais concludes she can no longer kill her. She tosses Bell a potion and lets them go.
Bell and a healed Wiene meet up with Haruhime, Lili, and some Xenos who got separated from the main group, and Bell and Wiene say goodbye one more time. This time Wiene tells him she won’t cry while they’re apart because she doesn’t want him or the Familia to worry about her. Haruhime suggests Wiene and Bell pinky swear that they’ll meet again.
Unfortunately, that might not happen, as throughout this whole operation, the trickster Hermes was playing the good guys like a fiddle. The main Xenos group encounter a dead end that wasn’t on Daedalus’ map, and Hermes arrives with Asfi to confess he faked the map to corner them. He condemns the Xenos as “heretical” and politely asks them to die. As expected, he has his own personal agenda, and he’s making his move.