This is in regards to the new challenge. I was curious as to what defines a secondary weapon, I realize that the Pistol, plasma gun and boltshot are secondary weapons. Considering there is a package to use a primary weapon in your secondary slot (I forget the name off the top of my head), would exchanging your pistol, for example, for a DMR on the battlefield make the DMR a secondary weapon?
I guess what I am asking is, is it the weapon itself or the secondary weapon slot?
Weapon, ie a Pistol of sorts 
No, secondary weapons are only the magnum, the plasma pistol and the boltshot. Per definition, a secondary is a weapon that you use only in case of emergency (for example you take out the magnum when you finish ammo in the primary weapon map) or as help in combat (the plasma pistol for example it’s a great help to disable vehicles/remove shields). This shows also why the Boltshot is kind OP, as it’s so good that can be used as primary…
The package you mean states that “allows you to pick another Primary Weapon in the secondary slot”, so it can’t be a secondary weapon, but you get 2 primary weapons XP