#wwgotyourback

My props: one blue dress, albeit of a different style than the one Wonder Woman wears; one yardstick, 36 inches in length and just shy of two inches in width; two binder clips, of mid- to large size; and one cardboard core from a paper towel roll.

[Image: on the left, a yardstick with binder clips attached at 28 inches as a makeshift crossguard; on the right, my hand holding the yardstick against a flattened cardboard roll with binder clips attached to the roll three inches in.  By slipping the yardstick into the tube while keeping the binder clips the same distance from the edge of the roll, I was able to accurately extend the yardstick to mimic longer blades.]

[Image: side-by-side stills from the 28″ and 31″ videos linked below, showing me in my blue dress with the yardstick resting in place alone (left) and with the cardboard extension (right).]

In regards to appearance and general movement I can certainly confirm that the idea does not constitute concealed carry, and that sitting down is off the table while the ‘sword’ is in place.  I was, however, able to get down on one knee and touch the floor, such that I would be able to pick up anything I could manage with one hand (such as a purse, a piece of paper, or a small to mid-size Plot McGuffin).  It does highlight the line of the ‘sword’ along the top of the back but is perfectly physically doable as long as the dress isn’t both skin-tight and inelastic.

As stated in the original photo set, walking is not an issue and basic upright dancing is also fine.  The sword is of course hugely obvious for any motion that involves bending forward at the waist, given that it does not bend with you and instead sticks out behind, but you can certainly do so without harming the dress if it’s of a suitable style.  Bending backward at the waist won’t get you very far, but it can be faked somewhat with a backwards lean instead.  There's a distinctly flat line to your back either way, but again a dress designed for such a thing could disguise it to some extent.  (Also, dancing with/being dipped by a partner would allow the line to be hidden a bit by their arm).

Now, as for physical/technical problems.. I think, for starters, that there may be some confusion as to the height of the hilt.  The original photo set used a dress with a low-cut back and a sword with a somewhat short hilt, which combined put the end of the hilt mid-shoulderblade.  As shown in the Wonder Woman trailer, however,...

[Image: Wonder Woman trailer still, showing the back of Wonder Woman’s blue dress, complete with sword, from the waist up.]

...the dress Wonder Woman wears is still somewhat low-cut but not quite as much, and also the hilt of the sword is long enough that it reaches to the top of her shoulders.  This changes things!

Reaching over the shoulder is now not only feasible, but functional.  And while I grant that bodies differ and I have somewhat longer arms than average for my size, I was able not only to draw a 28" ‘blade’ (the functional length of the yardstick as blade+hilt), but also 31″ and 33″ ‘blades’ once I extended the yardstick with my cardboard tube.  The 33″ draw is a little bit of a stretch, but mostly because the yardstick does not taper.  I do not have a sword to test with, but I think it would have been a lot easier not having a corner popping the hem like it did.  (Also it’s not quite as smooth because I kept hitting the doorframe next to me if I wasn’t careful, whoops!)

In all three cases, I was able to draw straight up for all or the majority of the blade’s length, with just a bit of a sideways finish needed for the longer draws to be completely free of the dress.  Not once while dancing or moving about or drawing did the yardstick get tangled or caught in the fabric of the dress.  I am unable to draw the 33″ version quite as quickly, but even slowly and with care for the doorframe (and no more than two or three practice draws) it only took five or six seconds.  (In comparison, it took three or four seconds to draw the 31″ and 28″ ones, which were also done slowly to show the smoothness of motion.)  I would not want to draw live blades of any length without practice and a blunt blade to practice with, and also preferably actual swordswork experience, but from what I can tell it actually is plausible*.  ^_^

*This assumes a scabbard incorporated into the dress design.  As you rightfully pointed out, a bare blade would be a very bad idea for anyone who is not a superhero (and even a few of those).