In Star Wars Episode III: Revenge of the Sith, General Grevious
is seen with four lightsabers: two (2) blue and two (2) green. As a
matter of fact, General Grevious has several more lightsabers of
different colors. His first weapon was the blue lightsaber of Jedi
Sifa Diyas, the Jedi who contacted the Kaminoans to begin
production on the clone army. He also took lightsabers from Daakman
Barrek, Tarr Seirr, Sha'a Gi, K'kruhk, Nahdar Vebb, Walden Brigdar,
B'dard Tone's unnamed Padawan, T'chooka D'oon, Jmmaar, Quarmall and
several of his younglings, B'dard Tone, Flynn Kybo (T'chooka's
Padawan), Soon Bayts, Roron Corobb, Foul Moudama, Roth-Del Masona,
and B'ink Utrila.