Hmm, I think in a better more just world that cared about rehabilitation, what Jasna did would be incredibly immoral. But in current day Roshar, I can't really find fault with her actions. The way I see it, there's two ways things could gone down. Jasna simply kill the men. Or, she cripples the men, takes them to the local law enforcement who then summarily execute them w/o trial because they're not going to doubt the word of Alethkar royalty. Neither options strike me as more moral then the other. They're both end with death, only one needlessly involves a disinterested & not all that just third party. I simply do not understand why bringing in law enforcement would be so important.
Also, I noticed people mentioning how Jasna could've disabled the men and I find this mindset odd. Jasna is an Elsecaller. Her abilities (transformation, transportation & shardblade) don't really give her the ability to disable a person w/o injuring them. So, if she did try to subdue those men, they most likely would've ended up crippled or severely injured. Imo, a quick execution is better then spending a few hours/days crippled by a shardblade then executed...