I attended the signing, and while it wasnt realistic to lurk about during the whole signing to see what questions he answered, here is what he gave in response to my own:
Q: What is Odium's edge. Vin and Ati killed each other but Rayse has downed 3 shards and survived. Was it skill, ability, numbers or possibly un-dispersed power?
A: Some combination of the above
Q: Could Sazed take down Rayse since he has two shards?
A: Rayse is VERY scared of Sazed. However, given Sazed is a coposite of two diametrically opposed shards, he finds it very difficult to act.