Fair Use1. The purpose and character of the use is both non-commercial and educative (well, it's educative for me at least..)
2. Not sure 'bout this clause.. the description is obscure at best.
3. Amount and substantiality. Anyone to do this will virtually have to think up a 3rd dimension and the original pictures can't be used as texture because of their size... I'd say I'm pretty safe here, the models will practically be a whole new thing when compared to the original artwork.
4. Effect upon work value. Well, Oblivion's an pc game, Anima's a tabletop game - I personally think that these two markets don't overleap enough to make the tabletop loose any value and I also think that this not widely known game will benefit from this more than anything else...
But yeah, I'll ask him as soon as my hands are free of other more pressings projects of mine

. I might eventualy do every single of his weapons and release it as an armoury.
I was actually thinking about creating my own armoury mod for the longest time. (Amongst other things.... I wish I could clone myself

)