It should be standard on the right security shoulder.
Captain
Primary: Blue Secondary: Silver
You can buy the shoulder, but you cannot use the knife, it is purely for looks. They are part of the Security armour set. You unlock it at General rank and can see it at Brigadier. There's Left and Right. Left is mirrored and has no knife, and costs 70,000 credits. Right has the knife, and costs 270,000, presumably for being incredibly awesome.
I'm sorry bud but there isn't a cheat code to unlock all the armour in Halo. PERIOD.
It should be standard on the right security shoulder.
You have to be a general, and you can only get the knife on the right shoulder
Captain
Simple: you must be rank commander or higher. Emiles helmet is a helmet of its own.
It's called a Kukri knife and you cannot use it. Unless there is some kind of mod or something like that.
Jorge wears Grenadier
For EVA u hav to be a major but Emile's helmet with da skull on it u hav to be i think a colonel
armour lock. if your playing on hamorhage
the halo reach legendary edition comes with extra armour for Spartans and elites as well as a model of Nobel squad
right now im using all odst which is my favorite armor in halo.
Primary: Blue Secondary: Silver
jet pack in haloi reach is an armour ability piick one up or spawn with it.