Board Thread:General Discussion/@comment-26569765-20170211235202/@comment-25926288-20170212003235

You can kill someone when you rip out their heart. Rumple tells her that if you do it right no harm should befell the subject, unless you will it. Cora "killed" the Safe Haven Villagers by brutally ripping their hearts out. I tend to see enchanted hearts as a proxy for the life force, less so the actual heart. But it's more likely that no real thought has been put into this matter. I mean, clearly the lungs or rib cage would get in the way. Chances are it's literal just like the shadow, but that's weird too. Rumple cut off his shadow and the show edits out anything the actor's shadow would be present, but I'm not going to think to hard and see if they always have edited out Peter Pan's non-magical shadow.

Anyway, Regina likely killed him swiftly because you have to be swift or your emotions get the better of you. Swift anger/bloodlust/desire or emotionlessness. Plus, I doubt she wanted to actual see her father suffer...