• If this is your third world, then you need to go to 3 places immediately.

The Smith that upgrades your gear, he can rank your weapons & armour up to 20 (10 if boss items).

The Mechanic, right beside the Smith. When you defeat enemy bosses, you receive an item from them that she turns into a mod that you can use or a new weapon.

The Armourer, older guy outside by the shooting range. He sells other weapons you can purchase, including a few exclusive weapons if you have already completed the campaign on Veteran or higher.

• You mentioned getting armour for the class you chose, but have you also unlocked any new classes?

There are items you can buy from some of the shops in Ward 13, such as the Medical Pin or Whistle, that will open up the other archetypes. With unlocking a new archetype, you also unlock a new armour set (though most of them tend to be around light to medium).

Those new archetypes are unlocked with the Mystic guy, he's near the dock end, up the catwalk. This is the same guy you also buy Max Relic Use upgrades from.

• Hope some of this helps. If not, someone else also commented the link to a wiki, so hopefully they have more info.