[Vergil glances at Nero, hesitating on just how much he should say given both that there's a degree to which this is his conversation to have and... Well. There will be time for that later. Vergil meets Kyrie's gaze.]

Those born of devil and man are not born with the ability to access the full extent of their demonic power. It awakens within them eventually. That surge of power in someone like Dante or me is strong enough to bring someone back from the edge of death.

[He gives no direct indication if that's speculation or factual. The distinction is irrelevant as the broader point is that if a half-demon could evade death, certainly a quarter-demon could replace a missing limb.]

In awakening the devil within him, Nero was made whole. As was his body once more.