Cortosis weave armor/weapon > current lightsaber.
Still depends on the amount of Soak Value the target has.
Soak Value of 5 (Brawn 3 + laminate or heavy battle armor) still means that at least 6 points of damage is getting through on a successful attack with a ligthsaber. And so long as 1 point gets through and the 'saber wielder has a few Advantage to spare, that means a critical injury with a pretty good modifier to the roll, on top of the weapon's Vicious quality.
Saw an instance where a decently-trained Jedi Knight-in-training only scored 1 success vs. a Soak Value 7 opponent (Phase 2 Dark Trooper) that only did 4 damage... but he had 7 Advantage on the roll, and used that for a crit with a +80 modifier to the roll. The exact same sort of thing could occur with a Brawn 4 Marauder with a couple ranks of Ferocious Strength and a properly modified vibro-ax, and that vibro-ax is a lot easier to acquire and upgrade than a lightsaber would be.