It's the same principle as for the Eye in the village: you either need to get four citizens to vouch for you, or you need to challenge the keeper of the Eye directly.
I believe that only a sorceress (or a player with magical ability) can challenge Aurvandel, but if you have all the spells for his puzzle game, it's super easy.
If you want to do it "
properly"
(and I guess it's the more honourable way?) you have to help/prove yourself to four of the citizens of Fornsigtuna:
Volund:
Click here to view the secret text
×You've already save his son Heime, he'll vouch for you if you ask
Lithrasir:
Click here to view the secret text
×You need to reunite her with Liff. If you accomplish that, you'll kill two birds with one stone, since it will also get you Liff's approval for the other Eye.
Snorri:
Click here to view the secret text
×You need to beat him in an archery contest. Meet him at midday at the target - and read the dedicated thread for some tips.
Arngrim:
Click here to view the secret text
×I haven't done it myself yet, but I'm pretty sure that if you cure him, he'll be able to return to town, and he'll vouch for you. Once you reunite the lovers, you'll unlock the means to cure him.
The Jarl:
Click here to view the secret text
×I have no idea whether he can vouch for you, but if you save him from the huldra, there's a fair chance that he will.
And I think that's everyone? Hervor can't vouch for you since she's, ah, not from around these parts, and Heime is not of age yet so he can't vouch for you either.
Hope this helps! If you need specific details about how to accomplish certain tasks, I'll be happy to oblige, to the best of my knowledge.
[Last edited by PicaLudica at 12-31-2013 12:32 PM]