ok, so the other day i got up to 39 outta 79 achievements, but that added up was really 37 OG's and i had one vidmaster(lightswitch) and double double, both DLC, giving me a total of 39. Now, ive read the first post and thought it could pertain to me, but it doesnt. I just recently got three more achievements since this, all legendary (except for not so fast buddy) achievements, and i still have shoulders.
Now to get it straight, im not complaining that i unlocked them early, they're my favorite permutation ever. But i just wanted to let you guys (bungie staff) that the ledgendary achievements for-some-reason work to unlock the security armor and the katana.
for another example other than me, here is a friend of mine who it also happened to.
http://www.bungie.net/Stats/Halo3/Default.aspx?player=Blood%2 0Letterr