I WILL talk about this for as long as I want to and NONE of you can stope me.
Anyway, I think another reason the scene is so effective is
a) one of the main characters (David) FAILED in his Really Important goal/objective which is always worrisome in books (or at least, in the ones where you want the protagonists to win)
b) we have, in fact, seen David successfully summon and control demons. Yeah, they were lesser ones but the books are Very Firm in establishing that demons and magic and the stuff are David’s area of ~e x p e r t i s e~. Him failing here is not just failing, but failing in an area where his control previously has been shown to be rock solid. And! That leads to the next one in that we’ve had an established pattern for this sort of thing which is thrown off! Disregarded!!
c) The main one (for me). We spend. So much time in David’s terror. And he is!! He is so terrified!!! The actual ‘hand being bitten off’ happens in a sentence, maybe two? The point is, it’s quick. But David’s pov of this? The build up?? We spend out sweet time in that period of tension amd terror and good grief is it effective!
d) decided I had more things to say, actually. Well, okay, just one, but still! Alright, so remember when I was lamenting how creepy it was that Astorath was acting weirdly parental? Okay, so part of the reason why I said that is that Astorath admonishes David (gently, almost) for thinking he could control ASTORATH’S power and says, hold on, lemme grab a quote—
said Astaroth, wagging a long-nailed finger. “For shame. Did you really think you could compel me to come running? That hasn’t been managed for quite some time, my friend. Do you think you should be punished for your arrogance?”
^^says that, and David responds with
“No,” whispered David.
“Speak up, child.”
^^^THAT. He says no!! He says no and it DOESN’T MATTER
“No,” repeated David, furiously wiping away tears on his sleeve.
“Shhh,” said Astaroth. “There’s no need for that. Come closer.”
David stood rooted to the spot.
“I had thought you might see the error of your ways, but here you remain stubborn and willful. Must your friends suffer for your arrogance?” inquired the Demon.”
^^!!!?????!!!!
LOOK AT THAT. LOOK AT THAT. THE SCENE CONTINUES AFTER THIS. FOR A WHILE. It is only on the next page that the hand chomping occurs. Just. Ahhh. I’m sorry, this excerpt is just genuinely so incredibly terrifying to me that my brain has uh…not quite moved on yet.