When a Psyker manifests Fearful Aura and gains Fear(2), does that inflict a Fear test on the members of the party who can see him?

That's my interpretation. I tend to be a bit flexible with 'who's effected by what Fear' with the bad guys (if they've been working around the boss's pet bound daemon for a while now, I think it's reasonable that they are no longer effected by its' Fear Rating, for instance- unless it turns on them...); but with a suddenly-manifested supernatural effect, I think it hits everyone.

I suppose it is like friendly fire. If you were going to spray suppressing fire at enemies, you'd yell "Duck!" - If you were gonna pull your scary face, you'd tell your mates to look away