If you want to switch between two or MORE weapons then you can use an Array within the Player blueprint. (UPDATE 2: This will work if you use the mouse wheel to switch or a button that must be pressed each time you want to switch.) Call this array you create EquippedWeapons and make the type as the MasterWeapon blueprint or the main weapon blueprint you used to create all of the child weapons from, but make sure it is of its class, not references.
Create two functions for this array called Add Equipped Weapon and Remove Equipped Weapon and give both an input of the type of your master weapon. Make these functions add and remove one item from this array that you choose through the parameters.
Now create your variable that tells you what weapon class is equipped and name it what you want as the class Master Weapon or whatever you named your master BP. Then go into your input settings under Project Settings and add one for next weapon. Once done, create, in the Player BP again, the input action event and add a script to check if the next weapon is existent, if not set weapon to the first in the equipped list.
If you do it this way, and add some nodes in to change the physical weapon, you have yourself set to have a switchable array of weapons equipped. You can also check in the Add Equipped Weapon event that the length is less than some number to limit how much you can have in your inventory. Let me know if you need any more elaboration on this.
UPDATE: If you want to make it even easier on yourself in the future, you can even make a new Component to attach to your player that does all of this for you, and set events to communicate with the component; and on Begin Play you can have your save function load the information into the component. If you want some help with this let me know and I can elaborate a bit more on the Component aspect.