Hmmm... my veteran rating was 1 which gave me the WWII weapons, but I didn't think anything else gave any more... I might be wrong though. Did you have any codes you could put into the redeem code part of the game which may have unlocked it?
nope no codes. I just had them already unlocked, and i still haven't earnt the points for them. TBH it seema a bit silly to have a medic class that doesn't start with med pack and defib. Perhaps you are supposed to start with them?