Archaic lightsabers commonly referred to as protosabers were the first known design of lightsaber. Like later lightsabers, their focusing crystal was set inside a hilt from which a blade of energy was emitted. The main difference between protosabers and later lightsabers was that the hilt was connected via cable to an external power pak due to limitations in power pack technology.
These lightsabers had limited power life and the mobility of the user was restricted by the cord linking the hilt of the weapon to the power supply.
As technology improved, the protosaber design was abandoned in favor of the modern lightsaber design, with some archaic lightsabers modified to remove the necessity of an external power supply. Some later attempts were made to reintroduce the external power supply using modern technology, trading less mobility for a stronger power source.
Protosaber design called for an external power supply that would be carried by the user on their back, hip, or belt. This power supply would be connected to the bottom of the lightsaber hilt, opposite of the lightsaber's blade emitter.
An external power supply was required for archaic lightsabers as no sufficient miniaturized power pack existed at the time that was capable of powering a lightsaber plasma energy blade. Even these larger power packs provided only temporary power, limiting the weapon's effectiveness.
Another limitation of the protosaber design was that the power cord between the hilt and the power pack limited the mobility of the user, preventing techniques such as the saber throw and telekinetic lightsaber combat.
At least one Jedi artisan eventually returned to the archaic lightsaber design, improving it with modern materials and engineering. The resulting weapon dubbed a "retrosaber", greatly resembled the original protosabers, but far exceeded their abilities. A retrosaber was just as potent as modern lightsabers, but offered a few advantages along with the disadvantage of the external power pack. The primary advantage was that modern belt mounted power packs allowed for a brief "power surge", creating a more powerful blade for a short time and therefore a temporary advantage in combat.