You start off with all your medals at 0. This is Green status.
To unlock an award weapon for a specific medal you must first gain 4 medals in that category to achieve Veteran status for that medal. Then when you successfully obtain the medal you will gain your award weapon. You must switch to it to use it.
Veteran status allows you to gain an award weapon and also gives you a 30 second grace period in which if you die, you will respawn with the award weapon. If you die after this 30 second grace period, you have to earn the medal/weapon again.
Elite Status gives you the advantage of lowering the requirement for that particular medal by 25% e.g. Elite status in Frenzy will let you gain the Frenzy award with only 9 kills instead of 12, therefore making it easier to gain.
Legendary Status allows you to permanently unlock the Award for that medal. You still start with the default weapon and must switch to the Award Weapon after entering combat.
Heroes cannot obtain medals, except in the case of the Mos Eisley Assault level, where you can earn Endurance, Guardian and War Hero.
These are all gained in Single Player mode. Can only be used on XBL if the server allows it.
Demolition : Unlocks Guided Rockets --> Obtain 4 critical hits on a vehicle in one life
Elite Status for --> Obtain 32 medals of that type
Endurance: Unlocks Energy Regeneration Bonus --> Obtain 12 points in one life
Frenzy : Unlocks Award Rifle --> Obtain 12 kills with the blaster rifle in one life
Guardian: Unlocks Damage Reduction Bonus --> Obtain 24 points in one life
Gunslinger : Unlocks Precision Pistol --> Obtain 6 kills with blaster pistol in one life.
Legendary Status for --> Obtain 64 medals of that type
Marksman: Unlocks Beam Rifle --> Obtain 6 headshots in one life
Regulator: Unlocks Flechette Shotgun --> Obtain 8 kills with a shotgun in one life
Technician : Unlocks Vehicle Regeneration Slice an enemy vehicle in one life(with fusion cutter)
Veteran Status for --> Obtain 4 medals of that type
War Hero: Unlocks Damage Increase Bonus --> Obtain 36 points in one life