After noticing a handful of people in the Halo community asking how to obtain the unlockable armor in Halo Reach. I decided to make this post, to show you how to unlock the armor in Reach.
Step one: Go to Halo Waypoint via the Xbox console, once Halo Waypoint has fully loaded, find your spartan (it will be to the left) and choose that option.
(note if you do not have it downloaded, go to the Xbox Game Marketplace, and search for Halo, Halo Wapoint will be one of the options listed, download it for free and continue with step one)
Step two: Go to the option of your Service Record, choose that. Once the service record has been pulled up, scroll all the way to the left. You will find a box titled Halo Reach Armor. Choose that box.
Step three: after it has been pulled up, you can then go through the armor, to see which armor pieces you have unlocked. At the bottom of the armor, there will be areas for achievements, if an achievement does not show up, choose that armor, and it will pull up a screen showing what achievements need to be obtained in order to unlock that piece of armor.
Step four: Once you have obtained the achievements for the armor you want to unlock, go back to Halo Waypoint on the Xbox, and go to the Reach Armor section, (follow instructions above if necessary), once it shows that it is unlocked by having all the achievements below the armor piece filled in. The last thing you do, is put in your copy of Halo Reach, go to the armory, find your unlocked item (being a helmet, helmet attachment, or chest piece), and you should be free to wear it anytime you please!!