Sorry, Demosthenes, I thought you were complaining about The Great Library itself, not BtL. (I suspect Dan thought this too.)
So the real explanation?
Um...everything Ares said. Plus, certain inhabitants of Covenant had the Codex in their possession (why do you think it's there in Homecoming?), so they knew that Alric was *going* to beat Balor and they built a commemorative statue in advance. And they knew how to train human bowmen from descriptions of the way they'd be in the Codex.
Happy? :-)
--SiliconDream