His stillness gives Sabriel pause- he's not attacking, or preparing to attack. So she lets the spell slip away, the marks fading back into the Charter, and she changes her grip, shifting her sword to a guard position- and revealing the inscription on it.

I was made for Abhorsen, to slay those already Dead

"Then what do you intend- and what are you? You feel neither alive nor Dead?" It's a puzzle- and a potentially dangerous one. Dead creatures are dangerous driven by their hunger for Life. But the man in front of her isn't hostile, and might be able to tell her where she is- and perhaps even how to get back.