Calligraphy is regarded as the most abstract and sublime form of art in Korean culture. The art is often thought to be most revealing of one's personality.
The correct word is revealing.(to make known, expose)
"of one's personality" is a prepositional phrase that tells "what" is being revealed.
Many people think that studying a person's handwriting style can tell much about emotional state, education, career and temperment.
Student or Learner