Yes, but those are a different kind of unit. Flawless Blades are the 3 man elite of the elite units. Comparable specialized marine units are Inner Circle Companions, Sanguinary Guard, Deathshroud Terminators, Exalted Eightbound... All of those have several weapon profiles, even the DA and DG ones, which only have one loadout.
And the Flawless Blades are supposed to be the best swordsmen of the Legion, or any Legion. If the rules didn't make a difference in the fighting style of those guys with one or two swords it would be soooo lame.