Like Guuchan mentioned, mainly that "up" activates abilities, while down scrolls through the selection. I've activated abilities countless times without meaning to.
I personally think changing to a WASD+mouse would be more intuitive, so you can aim your throws and also select abilities by hovering over them and clicking.
I mentioned aiming throws, because I have encountered a few time where i need to throw something ahead but ends up dropping it and vice versa. Would be nice if I can have more control over where i throw. If aiming vertically can cheese some puzzles, maybe limit it to horizontal, but show a guideline so that I'd know at least where it'll end up.
Just my 2 cents. These are big changes though, so it can prolly wait till post jam XD