Dual phase sabers had 2 focusing crystals in them allowing the length to be adjusted in combat with the flick of a switch. Corran Horn used one and, if I’m remembering correctly, Kanan shortened his saber for Ezra to use. If there was a double bladed with dual phase it’s totally possible.
They should build a cannon which fires out a sphere which then has a dozen foot long lightsaber blades ignite across it whole surface. Imagine one of those rolling through the enemy ranks
Exar Kun literally invented the double lightsaberor at least was the one who made it well known, right? He had to learn it from a sith holicron, so later jedi probably used exars design