Hiccup didn't really want to do this to Dipper, but they couldn't have him hovering there in the state he was in. Both the ring and years as a Viking were telling him there was only one truly compassionate thing he could do in this situation.

"Sorry about this buddy," Hiccup said, speeding forward, staff brought to bear. With one fell swoop, he brought it up, and swung it firmly down on Dipper's head.