What James wouldn't give for ten minutes alone with him during which he was prevented from trying anything violent.

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.