[Well. Mal isn't expecting that. In dreams (and unbeknownst to her so far, as Cobb's projection) her reflexes are quick and dangerous; in the waking world, not so much. So even though she flails at Arthur with the pillow, it's too little, too late. The gun connects with her head hard in exactly the right spot, and she drops to the floor, unconscious.]
[Arthur, you've got a funny idea of "no lasting harm".]
SPAM
[Arthur, you've got a funny idea of "no lasting harm".]