In Game: https://imageshack.us/scaled/large/43/wowscrnshot060913030243.jpg
I went back and equipped 2 fist weapons
In Game: http://imageshack.us/a/img600/246/wowscrnshot060913030820.jpg
I then went back in and switched the 2 fist weapons to really show the difference between the two:
In Game: https://imageshack.us/scaled/large/802/wowscrnshot060913031140.jpg
I hope this helps fix this annoying visual bug on the Armory.
Edit: Had to redo the Armory images since the image I linked updated every time I logged out. Had to save the image after each log out and upload them separetly.
Edit 2: Just for thoroughness, thought I would do a Fist in the Main Hand and a Mace in the off-Hand and everything seems to be working. Lack of "Pose" withstanding though that is something else entirely.
In Game: https://imageshack.us/scaled/large/32/wowscrnshot060913033034.jpg
Edit 3: One thing I thought of that could be related was dealing with the transmog of changing all "off-hand" weapons to "one-hand" weapons and there could be an issue in the code when dealing with fists and off-hand slots.