During a match, you will sometimes get medals or 'honors'. As you progress through the single player game, you accumulate these. When you get one, a small version flashes over your head for about 2 seconds in the game. They are also displayed at the end of the match.
Completing a match with better than 50% accuracy
Fragging an opponent within 4 seconds of a previous frag
Awarded after each 100 frags earned
Punching someone to death.
Awarded for every TWO successive railgun shots
This is winning a game without being fragged (or suicide)