Disarm her first

You hop past her in a split second, removing her staff from her hands. She grasps at air for a second before seeing her staff is gone, and you can see panic wash over her. She holds her hands in front of her defensively, but she probably knows it's no use.

You reveal yourself from behind your hidingplace, holding up the staff. "Looking for this?"

"Give it back!" The diviner demands.

You point it at her, and she immediately jumps back, holding her hands up as if she's gesturing for you not to fire a weapon at her. It must be a powerful staff indeed. You run your hand upon the shaft, and though you're no wizard you get a sense of the magical power within, and how to will it to activate.

"I wonder what this thing will do if I use it. Does it spit fireballs? Lightning? Torrents of water? Turn you into a frog?"

The diviner backs away another step, whimpering "It's an elemental air staff, p-please point it away from me!"