Slowing down with the sax made sense for me, as someone used to Touhou Project with being able to switch between a slower (focus mode) and faster (default) speed.
I was fine with the keybinds for solo play but obviously I am just one data point.
I think the ease of use of each weapon is exactly in left-to-right order, how it is displayed on the weapon select: Shoe Gun, Saxobeam, and Joust. Thanks for making this game, I enjoyed it! I got here from The Mane Quest reblogging your BlueSky post. I like the pixel art and retro theme, and the general horse theming instead of sci-fi. I liked the final upgrades all being the same color. And the synergy in co-op if you have overlapping shots.
I'd comment on the final boss, but I am having trouble doing the spoiler dropdown thing, hence all my edits. Also, I died right after beating the boss and got both the Game Over screen and the You Won screen.