Hmm well as far as I know he started out as a messenger god and later became a patron of sports and thieves, than he became the god of trade and painters than he became the god of the spoken word than calcullus and astrology.
If you need something to represent him how about a scale and weights or feathers because birds are seen as the messengers of the gods. How about a dictionary since he was a very eloquent god, or a quil.
Hope this helps,
"If you take a copy of the Christian Bible and put it out in the wind and the rain,
soon the paper on which the words are printed will disintegrate and the words will be gone.
Our bible IS the wind and the rain."