Eventually the entire house has been ransacked of statues, and the giant has clubbed into oblivion the wall that Aslan leapt over to reveal the spring landscape beyond, and Aslan says:
"Our day's work is not yet over, and if the Witch is to be defeated before nightfall we must join the battle at once. And now! Those who can't keep up - children, dwarves, small animals - must ride on those who can. Those of us with good noses must come out front with us lions to sniff out where the battle is and the rest must follow us. Look lively and sort yourselves."
James heads for Aslan, figuring that if he's willing to let her ride him again, he'll be the fastest and she'll be needed at the battle as a visibly human commander with a magic sword.
Bella goes, too, and presently they are Aslan-mounted again while everyone else piles onto the larger creatures and the sniffers range out ahead to find a trail. A hound gives a loud bay and everyone's off in that direction.
"Off my back, children," says Aslan, and when they have dismounted he roars to shake the whole of Narnia end to end, distracting the witch as she is just about to knife some poor animal and rallying the portion of the army she has been, till this moment, soundly trouncing. All the statues she has made in the battle so far are restored to life and rejoin the fight.
The roar would probably be quite enough to inspire the troops, but Bella lifts her staff and lights it brightly and finds that it disagrees very much with some of the insubstantial Specters and such on the Witch's side who might have been difficult for James to run through.
James takes in the lay of the battlefield at a glance, and perceives immediately where she will be most useful. She heads for Eternal Winter at a dead run.
Winter is the only one of Jadis's army, Jadis included, who is not in the least bit shaken by Aslan's roar. The area immediately surrounding him is littered not with statues but with bodies. He laughs when he sees James coming; she, for her part, is the only one of Aslan's army who is nearly that eager to approach him.
Bella, meanwhile, has no offensive capacity; she speaks through her brilliantly glowing staff to a unicorn who's limping enough to have trouble running, but not immobilized nor prevented from using his fantastic horn, and calls him over to her to guard her back while she does battlefield triage and administers cordial to hurt creatures. They throw themselves at the Witches' army as soon as Bella has them up again; she is to start very careful with the cordial, as the bottle is small, but presently finds that the level isn't dropping at all, heals the unicorn too, and drips a bit into the mouth of any injured creature on their side she can reach.
She gets close enough to Winter to reach him with her sword, predicts that he mightn't give her a moment to catch her breath if she tries to take one, and attacks immediately.
Whether he would have or not, he's certainly not shy about defending himself and counterattacking. With James out of breath from her sprint, and Winter a little tired from the morning's slaughter, they start off roughly even. But he has more experience, and more weapons; he fights with sword and dagger against her sword and shield, and when she disarms him of the dagger early on, he produces a smaller one from seemingly nowhere.
But she has no opportunity for that. And he's a rallying point for what's left of the Witch's army, and by himself he'd probably be enough to wipe out a significant fraction of their side, with the possible exception of the giant and Aslan. James wouldn't even bet that much on the giant. The only reason she has survived this long against him is that her magic sword is working at full capacity.
She ducks under a swing of his sword, raises her shield as he whips it back around, feels the impact like a massive hammer coming down on her arm - and - brings her own sword up, clean through his wrist. Winter's sword falls to the ground with his right hand still attached.
He giggles the whole time.
While he's laughing and admiring his new hand, James puts her sword through his heart. And hopes it'll take.
Where the blade emerges from his back, it ices over almost immediately; the whole sword becomes bone-chillingly cold, although the hilt remains clear of ice.
It's the only thing that does.
The ice spreads rapidly over his clothing and skin, until he is completely encased, frozen mid-laugh. He'd fall over, if his boots weren't iced to the ground.
She lets go with a hiss and looks around, hoping most sincerely that she won't have to fight anything else while her magic sword is otherwise occupied.
Soon everything is still except for the battlefield medic, who no longer requires her unicorn.
"James," says Bella through her staff, "you okay? Do you need some cordial? It lasts, it turns out."
"I'm - I don't know," she says, a little breathlessly. "I'm okay, I think. I got Winter but I'm not sure he's actually dead."
"We'd better ask Aslan about him. I've got a few more creatures to fix -"
"If that's what you'd call him," she says. "I'd kind of like my sword back, in case I need it again, but I'm not sure I could get it out of him even if I tried. Or what would happen afterward."