Interlocking hilt, also known as paired lightsabers, locking lightsabers, or form shifting lightsabers, were dual lightsabers that could be joined together at the hilt into a single weapon, either by a locking mechanism, becoming a double-bladed lightsaber, or by a fiber cord, where they would be flailed about by the cord.
Asajj Ventress joining her paired lightsabers during her duel with Mace Windu.
One of the earlier users of paired lightsabers was the Sith Blademaster Kas'im, who used the paired function to disguise his two lightsabers as a single saberstaff, before splitting it into two separate weapons. He used this tactic to great effect against Darth Bane on Lehon.
Komari Vosa was known to have wielded paired lightsabers. After Vosa's death, her lightsabers were given to Asajj Ventress by her former master, Dooku. The weapons included both types of joining, being connectible by both the locking mechanism and a fiber cord. Ventress often utilized the locking mechanism, wielding the weapons as a double-bladed lightsaber. Though she would normally use the locking mechanisim, when connected by the fiber cord, the weapon was more difficult to control than a regular double-bladed saber, however, the curved hilts and the fiber cord joint of her saber gave the wielder the benefit of striking from unexpected angles. Ventress' skill with the weapons was impressive, but not enough to defeat seasoned Jedi such as Mace Windu or Obi-Wan Kenobi.
One of the more recent users of paired lightsabers was the Emperor's Hand, Sa Cuis. However, it appeared that Cuis only used the paired function for easy storage, wielding his lightsabers separately in combat.
- Jedi Academy Training Manual