Hi, I just spent some time playing The Phantom Blade & I have lot of comments about it.
First of all, I loved the music and graphics & wouldn't change a thing about them. The music was especially good & fit the atmosphere well.
The gameplay was good. Jumping, attacking, and Phase Shift all felt good and were intuitive to use. The attack's range felt short, but it would probably feel better if there was more feedback when taking and dealing damage, such as changing the character sprite during invincibility frames, knocking back the enemy and/or character, sound effects, etc. I don't expect all that in a game jam entry so it's no big deal, and I'm sure you would've added that stuff on your own given more time. I had even less of that stuff in my game, after all!
I have quite a few criticisms, but I don't think the game is bad or anything, I just wanted to mention everything I could think of so that you might be able to improve your game with the feedback me & other players give.
The audio is very quiet. The voiceover is somewhat hard to understand because of the distortion effect, and it was made even harder since I had the volume on very low at the start. I would suggest having subtitles on the screen during the voiceover so that's not a problem. It might be good to turn the volume up too, since I had to increase it quite a bit from the level I had it at watching youtube videos at full volume.
A few glitches: The resurrection button doesn't work if you click away from the screen. I'm not sure exactly when that behavior happens, but it seems like clicking away during the end screen and then clicking back always made it so the resurrection button didn't work.
If you press "continue" after dying, you start over, but if you get to the chest with the Boots powerup, you don't get the powerup.
Edge grabbing was glitchy. It was easy to get into a position where I appeared to be standing, but couldn't jump or move onto the platform, I could only fall back off the platform.
Some jumps or falls are blind. I recommend making it so the player can always see where they're jumping or falling to, especially since you have instant death pits. You could also give the player some control over the camera to allow them to look up and down.
I had a few problems on the far left screen. On the right of the screen where you enter, if you walk all the way to the right on the bottom level, you can't see your character because of the automatic camera, but you fall into a pit and die. The other thing was on the far left side. There is gap between platforms that is very small and you can just barely fit through. I actually stopped trying the first time I got there and went around the other way because I thought you couldn't get through the gap. It would be good not to have gaps that tight, especially since the player can't really judge exactly how the player's hitbox and the platform hitboxes line up. One more thing that happened on this screen - I used up all my mana after killing all the monsters, and if you do that while on the bottom level, you can't progress anywhere and have to kill yourself or close the game window.
There were a few other things I'd like to see, but I didn't expect them in a game jam version due to time limitations.
It would be nice to let people use the d-pad on the controller as well as the analog. Unless the movement is actually analog (i.e. the character runs if you move the stick all the way & walks slowly if you move it partway) then it's just a matter of preference whether you use d-pad or analog stick, and many players, maybe even the majority, prefer d-pad with 2D platformers. It is easier to avoid accidental inputs for one thing. It's good to allow people with different preferences to enjoy the game the way they want to, and it shouldn't be too hard to implement.
I also noticed that in the first cut scene, there is a flashing light, and it might trigger epileptic seizures. I don't know a ton about what triggers it or not, but it would be good to allow the player to disable screen flashing in the options. Again, it's not something I expect in a game jam, just something to do when you have the time to add all the features you want in a finished product.
I would also allow the player to use the controller to activate Resurrection on the death screen instead of requiring the mouse, and it would be good to let the player skip cut scenes.
It's definitely a good start to a game, and I hope you can keep expanding it!