This is a great demo! As a veteran of 2D Soulslike Metroidvanias (my favorite niche genre) I have several comments on the gameplay and design:
The art is fantastic, but there are far too many intrusive foreground elements. Either remove them or add a culling mask so you can see through them as the player approaches. As they are now they are intrusive and can block important information like enemy placement and telegraphs.
The parry is great and easy to use, but it may be a little too generous. Consider shortening the range or tightening the required timing to parry. I would also decrease or remove the parry's ability to deal damage like an attack. As it is now, the parry is a bit too safe, offering damage immunity and output at very little risk.
The boss's drop attack needs a better telegraph. It's essentially down to the player to memorize timing to dodge it. Showing a telegraph indicator a moment before the drop would be better and allow the player to react instead of forcing them to predict.
You can spam the Heal key to heal much faster than if you pressed and held. This can be fixed easily by adding a short lead-up to the heal starting.
Spamming dodge is faster than walking, and because you can pass through enemies with it, it allows you to skip past them. Since the only thing you get for fighting enemies is healing charge, there is no reason to fight them if your potion is full. I would recommend adding some kind of Dark Souls/Salt and Sanctuary style stamina system to prevent players from spamming dodge for movement and to cheese encounters.
Verity's speed could be a little faster. This would allow players to traverse the map faster, and also would allow for more aggressive playstyles.
Verity's attack range is quite large and is kind of oppressive. I noticed almost all the enemies have attacks that involve lunging or jumping forward in order to cover the space. This isn't necessarily a bad thing, it just means that if you ever add a different weapon with a shorter reach, it will have to deal with the enemies large attack range. In most other games like this, the extended reach of a polearm is an inherent benefit of the weapon and makes attacking with it safer than a shorter weapon like a sword. Because the default in your game is the poleaxe, all enemies will have to be balanced around it and it will make any future short ranged weapons much more dangerous.
The "defeat" scenes are obviously set up in stages, but it's not clear how long each stage will last, which could lead to players skipping before seeing the complete animation. This is especially a problem since the boss's defeat animation (the first scene with Verity on the root), has only one stage, which can lead to players watching it loop for a long time expecting something to happen. Many other games with scenes like these will have an indicator which displays what part of the scene the player is viewing, and allowing them to skip to and loop through specific stages before exiting.
Also, this isn't a criticism but the default keybinds are super unique and took some getting used to. Usually these games use Arrow Keys and ZXC Shift Space Ctrl for their controls, some use WASD Shift Space Ctrl Mouse. Not bad, just different.