Greyhand.
Korgan would obviously dislike the talky options. Guy states that he came to kill you, you kill guy in a bloody manner. When you have to axe, axe, don't talk!
Ditto for Viconia - back in the underdark, those who went on insane Amok runs were put down quickly, or cast into the pits to do the battle they crave.
Aeri etc would be really sad about not being able to help the guy...
Generic good NPC ponderings... did we have to kill him... could Irenicus turn Imoen against you?
Oh, and obviously Viconia should have banter with the remains of her house in Ust Natha.
Edit - Changed "he" into "Irenicus" on account of not everyone living inside my head.