[thejeff]

Just thinking out loud here:
E9N4 may be good, but it's still oddly mixed. E9 is great for the Riders, but the N4 is largely wasted on them, though the drop in afflictions is always good. N4+ is nice regen for the Spiders, but they don't get much from E9. Your mages aren't sacred, so the E bless doesn't help there.
Plus you've got both paths already on national mages.

How about an Astral bless? That covers your main magic lack, getting you rings and late-game spells. Any MR boost is invaluable for the Spiders, if you go to S9, Twist Fate will help the Riders, since they're low hp.
Maybe add another minor bless if you want something else on the pretender.