More Star Wars: Jedi Fallen Order Guides:
How to Get the Double Bladed Lightsaber Location Guide
You can get the double bladed lightsaber very early in Star Wars Jedi: Fallen Order. Once you get to the first proper planet, Bogano, follow the story and go into the tomb. When you come out you'll go down the shortcut to the left. Along this path is a wall carving you'll inspect and this will unlock the planet Dathomir.
Head to Dathomir and follow the path I take to get the double bladed lightsaber for you to use whenever you like.