Well, they're based on the Bloodrayne blades.
Snip!!
Those are supposed to be machanical-ish, since they flick open and closed, as well as reverse into "Nemesis Enforcer" position instead of the ones shown here. But I confess I have no idea how that's supposed to work mechanically.
Eh, For the "pocketkinfe" version just; put a hinge right where the handle is, some "mechanics" to do all the folding/extending work in the long part that straps to the arm and add that extra strap at the wrist. then the blade would fold back into the forearm part and the handle would swing down and lock into place as a butt guard by the wrist. Then there would be just a bit poking out past the elbow, which i guess would be good for elbow smashes.....
As for the "cyber spur" version the blade part would retract into those "mechanics" from before in the same manner you retract cyber spurs. It would be like the the old Forearm Snap blades from the Street Sam Catalog.
I would imagine the damage stats would be the same a a normal sword. No reason they wouldn't be. But I would postulate that the fold up version is cheaper than the retractable one. And if we were going here I'm sure you could get this in a Vibro blade version.