If you're a jetti'kad swinging Mandalorian... hmmm. Well something that will take thw whack from a lightsaber fairly well, can be quite flexible would be leather. Depending on the thickness will make up the weight. It's not overly heavy but it's no ultra lightweight either. Simply make your armor templates and cvut the plates from leather rather than plastic or sintra or metal. For the breast plates, you can cut 3 or 4 strips that are connected with rings or rivets to contour to your body better. Also, if you wet the leather and form it, it will dry to fit.
Just a suggestion. ANY armor you put on will restrict movement and weigh you down. It's the trade off. You can wear a chainmail shirt with little to no restriction and little to no protection and have a full range of motion and abilities. However, evety piec e of heavier armor you add will cut down on the movemnet, range, speed and mobility but, it gives you added protection and allows you to take more punishment.
Personally, I say loose the armor and wear a robe if you want to be a Jedi. If you want to be Mano'ade, armor up and perhaps carry a heavy beskad to hack with.