Build a BasicWeapon Blueprint and make childs for every Weapon.
In the BasicWeapon Bp you implement all the Functions.
You WeaponInventory should be of class BasicWeapon so you can fill it with you Weapons.
Now you only need to call the funktion in the PlayerBP
Mouse1 Pressed - > GetActiveWeapon -> Fire
You can use a StandartFire or Reimplement it on each Child for Custom Fireing
Same you can make with all the functions. And its a better Way as implement it on the CharBP.
Thats all i can tell you without knowing what exactli you done in you BP and cant give you a example 
Greez DarkSoe