He was wearing the cuff so he had no magic…. And why did the dagger even harm Rump?
I’m gonna guess that Pan lost his magic when he transformed into Malcolm, and then the cuff was no longer active, and all the dagger had to do was pierce Rumple’s skin in order for it to take away his powers. (It’s a bit of a fanwank, but it works.)
Which…actually…does that official summary say that it did actually go all the way into Rumple’s heart or not? Because if it was just a surface wound…that sorta increases his odds of having his body survive.
ETA: Just looked it up. Official summary says…
He holds him close as he plunges the dagger through his back. It goes through his body and into Rumple’s as well. Pan returns to his original form. Magic washes over father and son until both are gone. Rumplestiltskin saved them.
Doesn’t specify that the dagger damaged any vital organs inside Rumple.
PS. I’ve posted about this in the Rumple Lives thread, because I figured the conversation would fit better over there.