The first thing that stood out was the fact that you have your Itch settings auto-loading the game as soon as the page loads, and the game itself goes immediately into combat. There is no intro or menu. There is no info on how to play or the controls. The page has info, but the game starts before you an really read through anything. If you want the game to go right into combat, then you should uncheck the Itch setting to have it auto start on page load. Since the jam is in voting and you can't alter the game itself, but can alter the Itch settings, I would recommend changing this setting on Itch.
This was an interesting concept. I wasn't sure at first, but it seems like it could be built out to a fun game. The arrows on the cross-guard were a nice touch, even though they are small enough I did not notice them at first. The marker showing your current charge level was also nice, though the blade changing color certainly drew the eye and was the more noticeable.
There is a sword icon at the top right with a number. Since you are collecting ammo, and it is a limited resource I had expected this to be your ammo, but it looks like a kill counter. I did not see anything that looked to show your ammo count. The gems at the center of the cross-guard does appear to change color based on your ammo, but not in a way that is fine grained enough to really judge how much you have left. I also found the cannon to be under-powered compared to the sword and not worth using, especially with the need to monitor ammo. I did not get beyond the initial enemies, so if you have ranged enemies it would obviously have more value for them. I didn't really notice much difference in the direction I charged the sword. It seemed to have its own logic for which way to go based on where the enemies were, so I usually just picked a key and used it all the time, rather than swapping between them.