I think they should add in the Haunted Helmet from Halo Reach. It was a really cool helmet and seeing how they are bringing back Carters armor from the game I think it is a small possibility. Honestly I was hoping that they would bring it back and make it to where you can only get it if you are an inheritor on Halo Reach because it was a real pain to get the highest rank in the game. A lot of people worked hard for it and I just thought maybe it should be passed down to Halo 5. If not, they can easily make a very hard task to get the Helmet in Halo 5.
It would also be cool to bring back the Original Recon Armor, and Hayabusa.
I know they were both favorited in Halo 3 so it wouldn't be a bad idea. I'm sure they can make the Armors look badass.
Hope you guys like my idea.