I found about this item from a friend in game, and I thought it was very cool!!!

its Jedi Knight specific as far as I can tell, here is a link to obtaining it

http://r2-db.com/guide/66/becoming-a-dark-jedi-and-obtaining-the-dark-jedi-lightsaber-jedi-knights-only

Unfortunately once you have finished the early part of your class missions you will not be able to get this, I rolled another to get this.

the Link OP is a bit hard to follow so in my next post I will have split it up so its easier to follow

I wonder how many other "Special" items/ things are in game like this that we have passed up and knew nothing about, is there a Sith variant?

I love stuff like this and would love to hear "read" about more like this

This is verbatim, I did not spell check or change it, just split it up, creditt goes to linked poster.

"When you first role as a jedi knight, You will not get you're very first light/dark side option until later on SPOILER( first story

quest kill the corrupted padawan then you get the hologram of the corrupted padawan master

Once you kill him you get you're very first dark side points now it is important to not make any Light side options for one of two reasons,

You want you're lightsaber in the end Now it may or may not be confirmed whether you can be filled with more light than dark but

in the end you're still in your neutral enlightenment So to be safe Make sure every good/dark side option there is you always pick dark.

Depending on how fast you progress through the beginning story mode, Mainly id pick dark side options just to be safe and if you're an Rper to build it up.

When you except the quest to explore the Ancient forge SPOILER You're master loses to his Former student and you must fight him,

When you defeat him He will tell you that you feel like you're the one to destroy the empire and know the true teachings of jedi

the force is strong in you blah.. blah.. Make sure you choose the answer What/Really?

But either of the options don't matter as long as you don't kill him or disagree with him

He ask that you let him teach you now you come across 3 options now this is the very IMPORTANT part DO not screw this up,

It will have 3 options One is to knock him out for the jedi council, Gain his knowledge and let him free. Kill him.

You want to select gain his knowledge and let him free

Now that's done your master wakes up and of course you lie to him saying he fell down the cliff and he's gone and dead,

Now this is the final part you can not mess this up! When he gives you the parts of the lightsaber and you will walk up to the

Forge, You again will have the options, Choose Bengel Morrs Option

If you have done all the following right, The cut scene will now show a green color crystal instead of a blue one. And you will

receive the dark jedi lightsaber(: "

so upon doing this mission series over (re-rolling) I believe you don't need to go dark side for everything till you are doing the the "forge" part of it, beat him, be amazed by his statement about saving the universe, then go dark side and help him escape and then select his mods when actually forging your saber,

(fun note* the creation music sounded dark side like, so that was pretty cool)

also the saber states forbidden to dark side 1 and above, just simply change out crystal

(I used the pre-order) and it becomes a neutral weapon.