Well, I'm not sure if calling them "stats" is accurate, but these are different parameters that have been mentioned throughout the novels. This info was gathered by a friend of mine for helping me write a fan fic, but I'm not sure where to put this on the Wiki.
Copy-pasted from http://pastebin.com/E6bTKha8. Probably slightly outdated since it doesn't take into consideration parts of volume 7 or anything from 8-10.
Strength [v2 Tohya]
Stamina [v4 Krusty]
Wisdom/Intelligence [v7 Shiroe] (The characters used mean both. Bit annoying since both are normal stats in an MMO.)