Shard is located inside Capstone Cave dungeon. Camp outside the cave is small but, there are still a couple of Black Dagger enemies occupying it. Inside, you can expect groups of two populating the dungeon. Collectible is inside the northernmost cave. It is just bellow the wooden platform. On top of this platform you may find Claudette the Sharper; a rather strong mob. Grab the collectible before alarming the group above it. “Jorunn the Skald-King” lorebook is on top of a wooden crate a few steps away from the wooden platform.
Capstone Cave approach.
Capstone Cave entrance map location.
Zoomed out view of the entrance location.
Sand Kingdom Moons - Super Mario Odyssey Power Moons