Upside-down M solved [maybe]

Abrac

Despite what Mathers says, the GD Ace actually looks like these examples from Kaplan Vol 1.

Aces of Cups

I'm not totally convinced Mathers isn't full of it. He may have actually seen a Spanish Ace with the design he describes, but I believe there's just as good a chance he made the whole thing up, especially the Egyptian part.
 

Teheuti

Despite what Mathers says, the GD Ace actually looks like these examples from Kaplan Vol 1.

Aces of Cups

I'm not totally convinced Mathers isn't full of it. He may have actually seen a Spanish Ace with the design he describes, but I believe there's just as good a chance he made the whole thing up, especially the Egyptian part.
Thanks for the photo. I love that there is a snake biting its tail around one of the cup stems! I haven't been able to find any example of twin serpents so far - although twin dolphins can be seen on many versions of the 2 of Cups. I'm not sure what he means by an inverted M on some cards - although a case could possibly be made for the chalice decoration on most of the French decks. The M shown in your example of the early Italian deck is formed by the water pouring up and out in two directions and water is Water (also Mem or Mari-sea). Waters of Creation is not a stretch in an Ace.
 

Abrac

The trail's heating up. I found this picture in Levi's History of Magic. Couldn't find anything about it in the text, but the caption says, "The right hand compartment contains primitive Egyptian Tarots—the 2 of Cups at the top and beneath this, specimens of the Ace of Cups." The ones in the picture are the Aces.

I'm still a bit confused by Mathers, but this helps at least.


 

Abrac

I found another example from Mathers of Binah being reflected into Hod. From Gilbert's The Sorcerer and His Apprentice, "The Azoth Lecture" by Mathers:

"This diagram (see below) represents the Trinity operating through the Sephiroth and reflected downwards in the four triangles of the elements. Air is reflected from Kether through Tiphereth unto Yesod, Water is reflected from Binah through Chesed to Hod, Fire is reflected from Chokmah through Geburah into Netzach. While Malkuth is Earth, the receptacle of the other three."​

Here's the diagram. The parts in red I added. http://s32.postimg.org/vt0thotdx/image.jpg

Waite's upside down M seems to represent several ideas. 1) It's Mem, taken from Mathers and the GD version of the card. Mem is also the Hebrew letter associated with Hod in both the GD and the FRC; 2) It's Mother or Matrona indicating Shekinah above in Binah; 3) It's upside down to illustrate the waters of Matrona reflected into the waters below, i.e. the soul; 4) Mathers says if the M is inverted it indicates "the impurity of the quintessence has been contaminated by matter." I believe Waite's take is a little different. He probably meant for it to show the infusion of Shekinah into soul and body, purifying and exalting them.

That's my final analysis. I consider this question officially solved, at least my main questions of where this oddity came from and what it meant to Waite. But being symbolic, the full depth and breadth can never be solved once and for all. :)