Your proficiency is on the 2nd page of the "Status" screen and is not the same thing as the Familiarity that you see on each individual weapon. The proficiency is specific to each type of weapon (there's one for swords, axes, etc).
Note that the proficiency keeps counting up after the bar is full. I haven't gotten this myself yet, but from what I've read, the number you are looking for to get this is 999,999 proficiency to max it out.