Hey,
Not sure of a better decal system, but as for applying a decal only to certain items…
One thought I had, you could put all items that you want to decal into an interface “BPI_Decalable”
Then, when spawning the decal, you could do a branch asking if the actor is within this interface. Use “Get all actors with Interface”, then loop this and connect to an equal node asking if the hit target is equal to an actor of this interface.
RGK