Why, sacred troops are 'especially devouted to God's cause', not the most successful munchkins around there.
Look at Pangaea. White centaur is identical to a centaur warrior, and has lower protection than centaur cataphract. And a lower attack, actually.
Anyway, its just a suggestion - I like vanheim (even though I dont play it often and hate playing against it), and its a pity that vans have become a dying out nation a whole age earlier than they should.
P.S.
To think of it, I'd be glad just to see a mounted hirdman in addition to a sacred van, helheim-style.