Odd. I was just playing a game as Russia, (who have the same bonus as Japan) but failed to see the difference. I made one archer without a barracks and made a second archer in a different city that had a barracks. Upon completion, they both had an attack of 1 and defence of 2.
Unless they only show the base values of a selected unit until you are in a fight...
Have to do more research unless someone can confirm...