This is my sword game: - YouTube and I’m trying to make damage system but I don’t know how I can do this ANYBODY CAN HELP ME?
There are plenty of ways you chould achieve this. Unreal Engine 4 even comes with a built-in damage system for Actors. You could use that, or if it doesn’t suit your needs, you could make your own. Without knowing the specific implementations of your project, it’s hard to give any specific advice.
Given that you’ve got networking and some less than basic animations going on, it shouldn’t be too hard to do either of these things. That is, unless you’ve copied most of the things and not made much of it yourself. In which case, your game might a bit too ambitious. If that is the case, I’d advice you to start with something smaller and learn the basics first. The only thing anyone ever achieves by starting out with something too ambitious is frustrating themselves to the point of quitting and giving up game development.
Maybe but I have to do this 
Anyway how can I implement damage system to the sword ? When I try to begin overlap to my character. I have bugs when I hit the other character its damaging self. Can you make example for me (picture) I really need it.
Honestly, it’s hard to answer without knowing the structure of your project. It could potentially be a big job, or it could be a small one. I don’t know what your blueprint classes look like or how you’ve coded what you currently have. Without knowing that, I can’t offer any specific advice on how to do what you’re trying to do.
I got sword BP and I’m coding damage systems , collision system(beginoverlap) in to sword BP. Begin overlap cast to My_player get refference from My_Player “Health” and coneect to integer-integer.
Honestly, it really sounds like you’re slightly in over your head here. Did you follow tutorials to get to this point? I think you might just need some more experience with the engine before you’re ready to tackle this project.