Arvil doesn't know what to do in front of someone like Amon.
Over his long life, he has met many people, most of them famous and powerful just like him, but compared to Amon, none of them made him feel afraid like Amon does.
And now Amon is saying he has a gift for him? He doesn't know how to feel. Amon calls his daughter his personal slut that he wants to keep around just to fuck, but then he goes and tells him that he likes her and wants her to be taken good care of. It doesn't make sense to him at all.
And how could it? Amon is not human. He is a god. An omnipotent being who can do anything he wants with just a thought. To him, all humans are basically a form of entertainment. He is favorable to the one he likes and ignorant of the ones he doesn't. But of course, Arvil doesn't know this about Amon.