I've been lurking around here for a couple days, trying to get a feel for the place, seeing just how screwed up the local populace really is. You'll be glad to know you are definitely screwed up enough for me to hang around. I've been a Dune reader for...oh, 15 years or so? Off and on, rereading the series in sequence, out of sequence, but I have never touched one of the KJA works - and judging from what I gather from everything I've heard, I would rather dig my eyes out with a rusty spoon than try.
So anyways...here I am.
It means mystery and prestige. It means power. It invokes a licence to act in the name of God.