Inside Obsidian Scar public dungeon. This place is hard to solo so you might want to bring some friends. Good news is that the shard is rather close to the entrance so you might just be able to get it alone. Bad news is that at the time we played the shard was bugged and it was not emitting the familiar shine. This might get fixed down the line, but keep an eye out because you can easily miss it or think you already picked it up.
Entrance to Obsidian Scar map location.
Skyshard is located inside one of the prison cells and as you can see it is not shining as others do.
Map location of the collectible inside Obsidian Scar
You can still pick it up although it is slightly bugged.