"Skill" would mean "Mastery + Endurance", right? (Originally Cunning + Endurace, until they unified the mainstats as Mastery.)

And regardless of whether anyone *can* make them, it's highly likely that there is approximately no point at all in doing so, since they will be set up for max-level 60, and therefore out-paced by modern augments, most (?all?) of which are better adapted to top-tier characters.