Lightsabers are weapons hailing from the Star Wars Universe. The weapon at first glance apears to be just a hilt, but upon activation a blade of plasma focused through one-three crystals appears.
History/Origin of the weapons:
Early Sabers:Lighstabers originated with the Rakata Empire, one of the first major forces within the Star Wars universe. These early lightsabers, known as Forcesabers channeled the darkside into a blade
through lab grown crystals. Following the discovery of these weapons by the ancient Je'daii Order the first Lightsaber was forged, using a special ritual to "freeze a laser" the First Blade was born.
Once the Force Wars occured and the Je'daii became the Jedi, these ceremonial weapons became an intergral ceremonial part of their order, however, blades of metal were still more used in combat due to the early sabers lack of refinement. The "frozen Blaster" technology was too unstable. They drew power from a belt mounted power supply and were prone to overheating relegating them to use in ceromony only
Bloody Christening of the Protosaber:This ended however with the birth of the protosaber. While these were more ungaingly than their predacessors due to their use of a more powerful power pack that had been perfected. However the cable restricted the movements and made force enhanced combat and use of force powers in combat difficult to impossible. However these weapons saw much use in the bloody war between the armies of the Jedi, and their foes of the time, the armies of the Dark Jedi. It could not be denied that the weapon gave warriors an advantage in close quarters combat, especially against heavily armored foes.
Rise of the Modern Saber, courtesy of the newborn Sith Empire:
Surprisingly the greatest advancement of the lightsaber came, not from the Jedi, but from a new force in the galaxy many thousand years later, the Sith Empire. The Sith introduced an internal power cell to the hilt as well as a superconductor, this allowed the saber to only expend energy when cutting something, solving problem of wasting power and eleminating the need for power packs on the belt. During this time the first schematics for double bladed lightsabers made famous/infamous by Darth Maul many centuries later, were drawn up. The Sith however rather than using natural crystals used synthetic crystals though some that would continue using their Jedi sabers or crystals. Ironically, despite the Sith pioneering the modern lightsaber Sith Lords of the era often still liked their Sith swords over the lightsabers.
The Jedi take up the Sabers of Light:
During the Naga's Shadow invasion and Great Hyperspace War the lightsaber inovations pioneered by the Sith were introduced to the Jedi defending the Republic. While it was many years before the Jedi adapted the innovations and removed protosabers (much like the Sith and Sith Swords) by the end of the war the Modern Lightsaber became standard for all force users. Eventually years of war between Jedi and Sith and the advent of the Clone Wars led to the Lightsaber becoming a more refined durable weapon of combat. The lightsaber as we know it was finally a reality.
Powers and abilities: The Lightsaber holds no inherant powers, it is simply a metal hilt and technology that channels energy into a coherant form that can form a blade, or whip in some cases. Few things can resist the cutting power of a lightsaber but such materials do exist. Cortosis, Phrik, Mandalorian Iron, and weapons made from rare materials or enhanced by Sith Alchemy or the Force. Water could also short out a lightsaber unless it was specially made. However the weapons were dificult to use without years of practice, as the blades were massless and it was easy to miscalculate an attack and injure yourself. As such Jedi were usually taught with specially modified training lightsabers. The blade of the lightsaber gives off no heat and used no energy unless it was cutting. The electromagnetic field containing the blade allowed it to cut without the beam being interrupted, it also is why other lightsabers would be repelled as if they were solid weapons clashing. Another interesting aspect of the Lightsaber is it would cauterize any cuts or wounds it gave, this was both a blessing, and a curse for the victim however.
Destructive Capacity: A lightsaber doesn't have a huge threshold for damage, it can easily cut through a person and most materials, so the capacity for damage depends on how it is applied however the weapon is at best wall level in destructive capacity.
Wielders: All Jedi, Sith, and Dark Jedi and War Dragon Riders use these weapons. Other people occasionally use the weapons such as the Mandalorians Pre Vizla and Boba Fett.
Materials: There 8 major components to the Lightsaber. These are the Lightsaber Hilt, Pommel Cap, Diatium Power Cell, Inter Power Insulator, Focusing Lens, Lightsaber Crystal, Emitter Matrix, and Blade Emitter. The Hilt could be any material the user wished allowing every lightsaber to be entirely unique. Another thing to note is that Lightsabers are generally forged by embuing them with the users force energy, pieced together and stabalized through the process. This creates an important connection between the Saber and the weilder and added to the uniqueness of each weapon.
Prerequisite for Use: Force Powers and or years of training are required for one to use a lighstaber. To truly master the weapon and the various combat forms a combatant must be focused and balanced, those who use the Force can create a link with their weapon making this easier and more natural. Few people without Force Powers can come close to matching a Jedi or Sith in a duel for this reason.
Notable attacks/techniques: Slashes, cuts, stabs.
Alternate Forms: There are several variations of the Lightsaber
The Standard Lightsaber: The mainstream weapon
Electrum Lightsabers: made with a special golden Electrum material hilt, examples: Darth Sidious's Lightsaber
Protosabers: archaic sabers with power packs
Double Bladed Lightsabers: special sabers originally used by only the Sith, has two blades. Examples: Darth Maul's Lightsaber, Savage Opress's Lightsaber, Pong Krell's Lightsabers.
Guard Shoto/Lightsaber Tonfa: a specialized Shoto saber with a handle at a 90 degree angle like a Tonfa. Exapmles: Maris Brood's Lightsabers.
Crossguard Lightsabers: special sabers with a second sometimes third blade that works like the crossguard of a regular sword.
Curved Hilt Lightsabers: Lightsabers with a curved hilt designed more for one hand dueling styles and variable angles to confuse the opponent. Examples: Count Dooku's Lightsaber.
Long Handled Lightsabers: Sepcialized Sabers with longer handle to provide more leverage in attacks.
Lightsaber Pike: Long spearlike lightsabers. Examples: Kazdan Paratus's Lightsaber
Sabercane: a lightsaber disguised and doubling as a cane.
War Dragon Riders Lightsaber: Modified lightsaber with two hilts and three seperate blades, one on each end and one connecting the weapons two handles together.
Training Lightsabers: special sabers on a permanant low power setting that can only burn or bruise an individual but not cut.
Dual Phase Lightsaber: Sabers that instead of having a full blown length adjuster like most can easily switch between two preset blade lengths in combat: Examples: Count Dooku's Lightsaber Darth Vader's Lightsaber.
Lightclub: The reverse of a Shoto, a massively oversized lightsaber blade used by extremely large Jedi or Sith.
Lightwhip: A modified weapon that created a longer flexible whip like blade, however they are weaker than lightsabers.
Lightfoils: special more elegant slender bladed sabers used by nobles on some planets, they are cheaply made weaker versions of the real thing and are usable by regular people.
Underwater saber: A special Lightsaber made to work undewater.
Darksaber: An ancient unique lightsaber with a flat swordlike blade as opposed to the normal round blade of a lightsaber.
for more information see: http://starwars.wikia.com/wiki/Lightsaber also credit to this site for a lot of the information.