Board Thread:General Discussion/@comment-50.72.49.241-20130930130812/@comment-16047389-20140127183541

Use of the Thu'um would not be prohibited during a challenge. Any Nord (probably any person at all) can learn how to wield it. The difference is that Ulfric dedicated time and discipline in learning it while Torygg did not. It would not have been cheating to use it.

However, that does not make what he did honorable or, depending on your definition, fair. Ulfric could have easily defeated Torygg in martial prowess alone. He had both experience and training that Torygg lacked. I think Balgruuf was correct, that Ulfric did so to prove a point. I will always attest to Ulfric being honorable and proud and etc. But his fervor leads him to very rash action. I don't know if he planned on using the Thu'um before the challenge was issued or after the duel had begun, but he did so to prove his strength and superiority, not because it was honorable or necessary.

So was using the Thu'um allowable? Yes. Was it right? No.