Be careful doing this. It seemed like I had some save game issues when doing it with the ultima pearl for some reason, so be careful and keep some backup saves!
Anyways, here's how you do it:
1. Make use of this saber duplication glitch on a saber that has some upgade crystals in it:
While onboard the Ebon Hawk, equip Visas with a lightsaber. Go to your workbench, and choose to upgrade an item. Go to the lightsaber list, and select the saber Visas has equipped. Select the color crystal, and change it to a different one and assemble. Select the color crystal again, but DON'T change it, just hit assemble again with the same crystal that is on there. This should cause an extra, duplicate saber to appear in your inventory. With the new saber in your inventory, save your game and reload it, and you will offically have the duplicate saber.
2. After you've done that about 10 times, disassemble them all and pull out the crystals.
3. Open up one of the empty lightsabers and put one of the ten or so crystals into the BOTTOM CRYSTAL SLOT and leave the top one empty.
4. Construct the saber and exit the workbench.
5. Go back into the workbench and open up the lightsaber. Place the exact same kind of crystal that you have in the bottom into the top slot.
6. Construct the saber then go back and look at it. One of the crystals is gone but the saber still has the bonuses of both, contained in the top crystal.
7. Move that top crystal to the bottom slot and construct the saber again. Then repeat steps 3 - 7 ont he same saber to make one massively powerful crystal.
Note: Things such as Regen and DC bonuses will not stack with this though.
