For the record, I am not hating on Arya killing the Night King. I don't think that's a terrible way to go. What I want to know is:
1. From when we left Arya as Melisandre was setting her on her way, how did Arya get out to the Weirwood?
2. If we just let that go and call it plot magic, how did she get past all the White Walkers without these seemingly, close-to-omniscient things sensing or seeing her?
3. If she somehow managed to pull that off, where was she coming from that she was leaping down, from behind the Night King, from that high up? What kind of vertical does she have?
I mean, there's a lot of leaps in logic to have that happen, but that sort of thing has happened a lot in GoT since about season 5 or 6. Emphasis has shifted from cool characters driving the plot with decisions that have real consequence, to characters going completely out of character to make a stupid decision that gets the plot to where it needs to be so we can have a "cool moment."