I managed to achieve a working solution without using the color matrix.
I created a separate sprite sheet that features only the lightsaber, rendered entirely in white. While the main sprite sheet is playing, I retrieve the current frame index of the character to locate the corresponding white lightsaber in the second sprite sheet. Then, I adjust its alpha value in the update method, and voilà!
There’s still some tweaking to be done, but it gets the job done without needing to modify the main sprite sheet.
I’m even considering adding a normal map to create some lighting effects on Anakin. 
"
