>>6754601>>6754602>>6754399The answer is easy, Anakin's first saber was designed with a single switch, but after continual war, he made the legacy saber with three switches, one standard, and two more physical buttons, in case he needed to give ti to Padme, or r2, or anyone else, this leads to the Finn "button push" and the red button on the opposite side of the saber, perhaps one of these buttons is for water-based combat, taking advice from kit fisto?
when he built the vader saber, he needed a firmer grip for his suited and gloved robotic hands to hold, and thus he built a beefier, harder on flesh version, with only one activation switch, because if he needed additional switches, he would be screwed anyway.