Are you sure that they are peacocks?
Peacocks would surprise me, Cranes wouldn't.
Cranes have a lot of associated symbolism in Far Eastern Culture, largely to do with long life, fidelity, wisdom, purity prudence and vigiliance, peace and happiness.
2 cranes emblem = lifelong fidelity in marriage
It is customary to make long chains of 1000 origami cranes for the those suffering a serious illness - there is a folk custom that folding 1000 cranes pleases the gods enough for them to grant a wish (normally recovery form the illness).
Cranes also carry Bhuddist symbolism - being the flying steeds of immortals, and the carriers of dead souls to heaven.
In Japan the Crane has long been an unoffical national symbol, it has/had? associations with princes of the imperial family.
Since 1955 the Crane has gained strong associations as an emblem of world peace. An 11 year old girl, Sasaki Sadako, suffering leukaemia following radiation exposure exprienced as an infant during the atomic bombing of Hiroshima began folding paper cranes , but died before completing her 1000. Her story is very well known in Japan.
http://www.sadako.org/
Post war Japan continues to have a strong pacifist ethic, and to a fair degree martial arts in Japan since 1945 reflect this, tending to have a strong emphasis on ethics and a philosophy of non-aggression.
A classic example of the use of the Crane as a school emblem is Wado-Ryu karate - (Wa = harmony/peace Do - way).
Then again it might be peacocks on the certificates after all; without seeing them I wouldn't know...
Hope this is of some help,
Dan