These are the following weapons that can be Dual Wielded.

1. Human Pistol (Weaker)
2. Plasma Pistol
3. SMG
4. Needler (Stronger)
5. Plasma Rifle
6. Covenant

When you dual wield you are bringing death to your enemies, but the bad thing bout dual wielding is that you can not throw grenades, Melee attack, and reloading takes much longer.