Word Watch 3, "abracadabra"

The history of this word, abracadabra, is seemingly as mysterious as the usage is magical. According to the OED, there is much speculation and little evidence of several claims of origin. Such an odd word, I rather expected the history to be quite thorough and interesting, including but not limited to a fascinating story of the origin of the word (how does one come up with abracadabra?) and intriguing tales of the word's travels and alterations. Rather, there is much speculation as to whether the origin is Latin or Greek, Thracian or Sumerian, Hebrew or Aramaic. Of course, there are cases for all. For example, the Latin abecedary means "of or according to the alphabet; alphabetic; marked with the alphabet; arranged in alphabetic order." I don't see a direct connection to magic, as a majority of the definitions link somehow to magic or mystery. But, while it's not the earliest usage, one definition of abracadabra is "obscure, nonsensical, mystificatory laguage; mumbo-jumbo, nonsense, gibberish." To me, abracadabra looks like letters put together, letters that are not alphabetical, but mixed up, nonsensical. This seems a stretch, but then again, if one squints, tilts one's head sideways, and blur one's vision, my explanation almost makes sense.

An interesting tidbit I discovered while on the OED website, is that the word abracadabra appeared on amulets. I was already aware of the magical connotation of the word, but that is was written or printed on amulets drew my attention. Abracadabra would be written over and over again, one underneath the previous, always dropping one letter, so to form a triangle:
abracadabra
abracadabr
abracadab
abracada
abracad
abraca (now there is a clearer connection to the Greek "abraxas")
abrac
abra
abr
ab
a
I am not sure if the triangle extended all the way to the single a at the bottom, but that was my understanding.
Interestingly, I am unsure whether the connection is incidental or not, cad is "a familiar spirit." I notice a connection of magic and spirits, though that may be due to my contemporary knowledge of the usage of both words. cad is surrounded by abra, but I was unable to find any meaning for the part-word. The symmetry is interesting to note, as well.

I may attempt more research into this one...