Lightsai

Background
The Lightsai was, in the ancient times of the Old Republic, considered 'The Ultimate Weapon of Defense' to a Jedi Knight or Sith. In the first Sith War, it was a common off-handed weapon that had its own unique fighting style, with a reputation of being the only Jedi weapon that could disarm another Jedi (or Sith), within a matter of moments after a duel started.

But as the Sith grew silent and thought extinct, the need to carry such a weapon died out and its unique style of swordplay went extinct as well. Not only that, but the knowledge of constructing them also became lost to Jedi History.

Construction
The Lightsai, at its core, was firstly designed with a shoto frame. This gave the weapon its small blade length. But what made the Lightsai so difficult to construct, was figuring out how to get two smaller blades to form from its sides.

Another speculation as to why this 'Ultimate Weapon of Defense' died out of popularity and knowledge, was due to the fact that it took a Jedi several attempts to overcome this blade problem, and sometimes a good six months to complete.

Some Jedi designs used three blade emitters in a single lightsai, so that if one emitter was cut off, the other two blades could still function in the fight. Other Jedi preferred special beam splitters that they created themselves, to separate the light into specially designed chutes, to create their unique blades.

However, because of the style of fighting, another obstacle Jedi had to overcome, was finding metal alloys that could resist lightsaber blades. At least, in so far as the outer hull of the weapon went. For a lightsai would be sliced apart easily, if a Jedi performed any basic Trap maneuver.

Cortossis was the main alloy that Jedi scrounged for, for this specific weapon. And only in areas of the hilt where the blade emitters needed protection, such as the Guard (which protected the hands from sliding up into the blade itself).

Because the lightsai took so long to create and some of the materials were very hard to come by, it was very rare Jedi wielded two of them. But in some of the ancient Jedi Knight Trials records, Padawans that constructed just one of these weapons successfully, often passed the Trial of Skill (even though that one is traditionally a test of swordplay in itself).

Combat
Because of the defensive nature of the Lightsai, for Jedi that used them for main weapons, Form III was the preferred lightsaber form. Though small stature sentients of the Jedi Order have used lightsais in Form IV as well. However, there is no mandated form one must learn to master this weapon, but some forms favor the lightsai more than others.

Firstly, the lightsai's unique style of fighting, revolved around a 'Circle of Defense'. The smaller one wields the lightsai around their body, the the stronger the defense against blaster bolts, most importantly. This is why most Lightsai practitioners will prefer Soresu over all other forms. Lightsais practitioners also focused on parries and diverting, rather than blocking enemy blades with brute force. Momentum, not strength, is the key to mastering this form, and overpowering your opponent.

Soresu, known for using the Force to energize and sustain Jedi for long bouts, gives the strongest tactical advantage to the lightsai. Against Sith or other Jedi, this weapon forces your advisory to keep a bit of distance from you, because of your Traps. This means you are forcing your opponent to engage in a longer battle, which plays to your favor.

It takes only one lock-on, to trap your opponent's blade, and a flick in any direction to disarm your opponent. And it is the reason that the Battle Masters of old found that forcing a lightsai wielder to reach in to them, was far wiser, and evened out the match.

The reason why some Ataru practitioners preferred the Lightsai is because the few that chose to wield two of this weapon, were able to incorporate acrobatics as a means of evading/diverting blaster bolts.

Lightsai flaring also looked more artistic in Ataru as well. Which was essential for the Jedi's defense. Training to twirl the lightsai around one's hands helped create the impenetrable defensive barrier of a Jedi, especially against blasters. This is also why the lightsai duelist will often learn Forms III and IV, because both forms tend to complete the training regimen of a successful lightsai duelist.

The only flaw to favoring Ataru more that Soresu, with this weapon, is that if the wielder is not short-of-stature, making more aggressive moves in lightsaber combat is more difficult because of the short length of the blades... Which is the same argument for any of the other aggressive forms.

Summery
Essentially, the Lightsai is purely a defensive weapon. One mastered in this weapon, can hold the line for retreating allies. They can outlast most other Jedi in lightsaber combat simply by trapping opponents' blades in theirs.

What a lightsai practitioner cannot do, is take on five Sith Lords and hope to win in swordplay. They do well one-on-one against Force Users and will go for the kill at the moment their opponent is at the brink of exhaustion.

To be on even footing, do not fight in their closest circles of defense. You will lose your blade every time, because there is no counter to Blade Trapping. If you force the lightsai practitioner to fight at your level, then it becomes a test of Your skill, not Theirs.