Blood isn't usually something you can just tack on to the nation. Don't worry about it with Arcoscephale.
You should have lots of Priestesses. Send them site-searching. That should give you something before or later. Once you have 30 gems, you can empower one to N2 and:
1) forge Thistle Maces, +1 N for anyone wielding it
2) start casting Haruspex, which finds ALL Nature sites in target province.
Nature 1 mages can cast Eagle Eyes, so if they don't have anything else to do they could do well as a bow-squad. Ethereal Crossbows are nice, but MR negates their special effect completely. Try combining them with few Black Bows of Botulf (Death item). Feeble-minded commander have worse magic resistance...
If you get Death/Air mage, Vision's Foe is wonderful. A crossbow with armor-negating damage, that also causes lost eye afflictions?