But - what about Willow? She was just tortured to within an inch of her life by the skinless remains of the man she murdered... and the effect upon her is apparently exactly zero. So why bother?

"I brought marshmallows! ...Occasionally I'm callous and strange." Laughing off soul-crushing terror is fairly characteristic of Willow. She dithers and panics when she thinks people are going to be relying on her in the future, but put her in an actual crisis situation and she's completly calm, ruthless, level-headed and focussed.

Plus, to be fair, we only see her immediate reaction - the comic ends within 10 minutes of Buffy freeing her. There may well be aftereffects...