Then on the the Elven healer. I had to deal with this, and I had no idea how I was going to do that. To stall for time - and because that was the way he had dealt with the brawlers - the Duke asked the elf to present her story of what happened. She admitted seducing the young lord, but for some reason, decided to play the "scared and desperate woman who panicked" card. He didn't buy that. The body showed no hesitation in her attack, no defensive wounds, no sign of struggle, no panicky stabbity stab stab, just a single clean surgical slice across his throat from ear to ear - the elf was a healer after all.
I still had no idea what to do as he demolished her arguments and told her to stop lying. Then he mentioned that she was an Elf, or as he said, "accursed", and that there were no Elves in his land. I didn't know why he said it, but then it all clicked. My subconscious had found the key that my conscious mind had missed.
This game is very Tolkien-ish - not Tolkien-esque. The Elves and Dwarves in the setting - as in Tolkien - were respectively immortal and long lived. The Elves were immortal as a punishment from the gods for fighting against them, while the Dwarves were long lived, with a short and precipitous decline at the end, as a reward for their noble service. If killed, the Elves were reborn with their memories intact - there was the matter of growing back to physical adulthood, but what are a score of years to an immortal. They could not escape this life, even if they wanted to.
Thus, death for an Elf was not a punishment, but a temporary inconvenience. A slap on the wrist. If he was going to punish her, and the Duke needed to, for justice, death was not going to do anything. He told her he would give her her trial, which was going to declare her guilty of the assassination of her son. She could say what she wished about this in public. Then her sentence would be announced and carried out, and it would not involve death.
That worked out perfectly - and all with setting appropriate reasons. I did not need to get meta at all. She can continue on, but she will have to deal with real and severe consequences. The party will have to deal with these consequences as well. Her presence will hamper them in ways quite visible. And I worked it all out subconsciously, while I was in character talking to her.