Thanks for help and lot of informations Rev0verDrive.
I’ve watch the video and read everything, but… 
Yes, I don’t like “but” me too! 
The inital statement is “I have a FPS Multiplayer template”, in this case the easiest way, on my mind only, is to modify the “On possessed” function in the “BP base character” and to switch on actual game mode before calling the event “Server Equip Weapon” and avoid it for a gamemode without weapon.
Of course, your answer is very good! because you can adapt weapons to specific game mode with more flexibility.
