Thanks for the clarification. Got the hidden room and that opened up the desert region properly. The first note made me think I had to do something similar with what I did to the moon coin to the sun coin.
Meant to say polearm. I got it from the statue in the southern region.
Also, possibly another bug I've found? In the calming monastery, there's the mosaic of a falcon protecting a ship. There's a door outline there. I did figure out how to open it, but there's no text to say something like if you use the opening spell, something along the lines of there's a door there, but the spell won't work on it.
One final thing. Ended up brute-forcing the engine room puzzle in the calm monastery., so I don't know if there was a guide somewhere I missed. How do you open the left-side door with the head above it (if you can)? I got a picture that looks like there should be a space to put the sun coin in the engine room, but I can't do so.
Thanks again for an excellent game.