FATE Rewards.

[WellFooled]

I may be wrong, but I think your reward is more about the contribution to the FATE than the medal earned. The other players netting more EXP probably did more damage to the monsters than you did. The medals though do determine other rewards. I remember reading about several different fates that only reward bonus minions if you can get the gold medal.

[Jundra]

Damage contributed would make sense IF, melee DPS wasn't at a disadvantage, and if there was an accurate way of comparing the effort of healing and tanking to that of DPS. I hope my first assumption was right and its based off the medals, if it isn't the system if fairly flawed. I know I have a horrible time trying to get a move off on a target before its dead.