DrunkenMage
Intoxicated Arch-Mage
There hasnt been a true high king for generations. Ulfric used a right he had, why didnt the others stop him then? He went in a city allone. Why didnt everyone attack him? Because it isnt illegal to challenge a man.
He could have used more underhanded methods
He went into the city under false pretenses. Everyone thought he was going to ask the High King to declare independence, since the High King does need the support of his Jarls to do something like that. So instead of declaring independence from the Empire peacefully, he challenged the High King which by Skyrim tradition if he refused he would of been removed by Moot. Ulfric however used the voice, something that has never been used in a traditional duel since the Way of the Voice forbids it. Which the way of the voice has been in effect since the First Era it is tradition also. The use of the voice is one of the major factors in which many Nords are against him and view it as murder.
"But a hero doesn't use a power like the Voice to murder his king and usurp his throne." - General Tullius