Didn't Jaina barely win against Darth Caedus while he was already dying from his injuries and was missing an arm? While Satele defeated Darth Malgus long before her prime? I must say, this is pretty obvious for me.
Yeah but his wounds were from Jaina with Luke's aid, and seeing as to how Luke is practically the god of Star Wars Mythos, that can't really be credited to her.
The aid was merely a simple illusion, making her look like Like, though. Nothing too major.
Also, the missing arm wasn't fresh as-of the final duel. He had medical care, and purposefully declined to have it re-attached because he could fight one-armed fine but reattaching it would require a longer period of recovery.
Not when they were engaging each other.
And sure, he could've made it a draw, but she was also noted to be going recklessly on the offense since he had escaped before.
Once she had cut his achilles tendon, she could've played it safer and still won, but didn't. Admittedly, tactical blunder on her part.