Socket refuses to attach anything

So I use one of the warriors from the Infinty blade resourcepack as my thirdperson character and retarged the UE4_Mannequin_Skeleton to it. I then created a socket in the skeletons hand were my weapon is going to be. Hower any soultion I use trying to attach a static mesh to the socket fails. I tried creating a staticmesh inside the TPC blueprint and attach it to socket under “Sockets” in the Details panel. Hower it doesn’t work as I get the message when I hover over it “Select a different Parent Socket - Cannot change socket on inherited component”.

Second thing i tried was making a blueprint class Actor and attach the mesh in there and in the Event Graph attach the mesh to the socket at overlap.

Link to that blueprint: Screenshot - 91f3889c967c5dd2d5aefb261cbbf9fb - Gyazo

Does anyone have some kind of solution?
I am very very new to this