(Noob Question) I’m new to the halo franchise and only played a little in the past. I can only enable the standard assault rifle and the side armarm. When I level up will I be able to use the other weapons like the dmr smg and the battle rifle and be able to use Shields etc? Also what’s the best way to level up warzone or Arena?
You need to unlock the ability to use weapons with req packs. In Warzone level 1 you can use the AR and Pistol, when you get to level 2 and you have unlocked it you can start with the BR. But you need to unlock them with Req packs. I got most of my unlocks with buying a bunch of Bronze packs.
If you unlock guns in warzone will you be able to use them in the arena and thank you for your help. 
The unlocks are only for Warzone.
I arena you cannot customize your load outs, everyone starts with the same and you just pick up weapons off the field. And there will also be power weapons that work off a spawn timer.
Ah right I understand so in arena can you enable armour mods or is that just in warzone because I’ve noticed some players take a lot to kill them in arena and I assumed they had some kind of armour mod