Another godot user! :P
Good game, I liked it! I obtained ending 1 and 3. And I guess I know how to obtain the second one... but no spoilers!
I think it is an interesting take on the theme but I won't elaborate here to prevent spoilers!

It is really ambitious to male a "3D-like" solo, and you managed it pretty well, no game breaking bugs or whatever! So be proud! However I have to some gameplay concerns :

• I think that the following "things" in the sea don't stop following you properly. One followed me to an island, with its eerie music and remained there. It was... well eerie!
• When in boat and going south, due to the placement on the ship and the 3D aspect, it was really difficult to see obstacles. 
• Because the animation of the sword are only sideways, it was really difficult to see were it was landing when facing north/south.
• It would be nice to have some visual indications, in addition to the willpower bar, of the player taking hits.

Anyway, nice work! Keep creating!