Ok, 50%, I was too excited
How does that affect the attacks then? Do attack 1-2-1-2-1-2... by rounds for each attack? If that's the case then you can finagle it to get your double attacks on the likely round you make 1st contact and still do some solid immediate damage.
I agree that F9 isn't a worthwhile bless here (even if you can get it pretty cheaply), I really don't see the point in going dual 9s though, I just can't see any of the other 9s being worth the cost, reletive to spreading a little between fire and astral to let your attacks hit more and help against magic. A low air bless might have some utility, and it gives you air coverage which otherwise you lack nationally, but I don't see it being that useful mid/late game compared to having astral.