In the cave, behind the wall of boulders, there is a pretty badly damaged statue holding a sword.
This is the low-spoiler guide for "Statue holding a sword" puzzle in Gibbous - A Cthulhu Adventure. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.