Kill'im, Shinin' Armor.
Kill'im.

"I don't know who you are. I don't know what you want. If you're looking to date my sister, I can tell you I don't have the right to keep her from doing so, but what I do have are a very particular set of skills. Skills I have acquired over a very long career. Skills that make me a nightmare for people like you. If you let my sister go now, that will be the end of it. I will not look for you, I will not pursue you. But if you don't and if you hurt her in any way, if you break her heart, if you do not stay loyal to her, I will look for you, I will find you and I will kill you."