Great idea.
In addition to your "completed assignments" button. I would like to see the same principle applied to the awards page (hide completed Ribbons/Medals), dogtags page (Hide completed), and weapon's stats page (see below).
Weapons Stats
:
Hide all weapons with more than 100 Kills (or more than 500 Kills). Helps players trying to achieve a service star for each weapon ( and players trying to achieve a weapons mastery dogtags on each weapon).
The buttons could look something like this
http://i.imgur.com/JKoCDdf.jpg