Beat it! Fun game, if a little slow in the later combats. Never found the bow upgrade guy, if there is one. I thought there would be a secret for sailing across the cave in the frozen north but there wasn't. I also got a bug when returning after getting the orb of the east where it immediately teleported me to that orb's destination and I couldn't re-enter the grove afterwards. I had just spent all my money on sword upgrades so when I found out that I needed 1k for the ship to progress I thought I would be stuck fighting goblins for ages. Luckily it fixed it self when I reloaded the game. ( I see in the comments below that someone else had the same problem and you fixed it. Thanks for not breaking saves!)
There's also a bug where the ghost castle is entirely optional-- the Skull Gate tile is walkable so it doesn't impede progress.