It's a mistranslation of the Hebrew word KOREN
Exodus 34:29 & Ex 34:30,35 in the Latin
In Hebrew the verb
1) koren = send out rays
In the translation the word KOREN was turned to KEREN , which is a noun meaning "horn." and they neglected its derived meaning
of "to emit rays." Many times in Hebrew one must assign the meaning of a word based on its context. In Psalm 69:31 KEREN is used to describe an ox or young bull. There the translation as "horn" is
appropriate. But in Exodus 34:29 KOREN is used in conjunction with the phrase "skin of his face." From the context of following versus the
meaning as "horns" is not supported. The Apostle Paul understood this
to mean "shone" and not "grew horns" as can be seen from II Cor
3:7-13.
As a result of this some Christian representations of Moses can be
found with ram's horns. Further, some have taken this image and used
it in their synthesis of Christianity with the Egyptian Amun and the
Greek Aries to form mystic cults.
Here is a HEBREW ENGLISH Bible were the word BEAMED was translated to HIS FACE SENT FORTH BEAMS
http://www.mechon-mamre.org/p/pt/pt0234.…
Here is another explanation
http://en.wikipedia.org/wiki/Moses_(Mich…