How to Get Double-Bladed Lightsaber early
Follow the main story on Bogano, until you reach the text in the Ancient Vault. Your next destination will be Dathomir. From the landing site on Dathomir, go right until you climb the ivy on the cliff wall. Go right and up until you climb back onto a cliffside. Next, go right and climb the two steps until you find an interior passage. Wall-run and jump inside, and climb more ivy up to an abandoned camp. At the top, immediately turn right and follow the path around to the large temple entrance doors. Be careful of the Nightbrothers inside. Proceed forward, swing across the gap, and take the ramp up. Instead of going forward at the top, turn and follow the upper walkway backwards until you reach a room with a campfire and stairs leading up. Go left at the fork, and enter another room with a campfire. In that room, wall-run and jump onto a branch, and use it to reach the upper level. Then, run by two doors and drop down through the left doorway. In the outdoor area, jump to a wall of ivy and onto a stone platform with a man in a black robe. Turn around, drop down, and enter a nearby hallway with a workbench. Use this workbench to change your lightsaber into a Double-Bladed Lightsaber, just like Darth Maul.