https://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/Arrays/ArrayNodes/index.html
Use Filter to sort by class.
If “Item” is your parent class, and Weapon, Armor, and Consumeable are child classes, then you can filter all items, all weapons, all armor, etc.
You can also have children of the Weapon class and filter all Axes, Swords, etc.