I finally figured out why the bones that the weapon is suppose to attach to isn’t working. Its turn out that I forgot to add the bones to the main mesh/armature model Blend file, only adding them to the animation Blend file. Once I added the bones and re-exported the model as a FBX file into Unreal Engine, the bones were properly working. The Inverse Kinematic controller bones that are incompatible with Unreal Engine are still there but they’re not really a priority right now or perhaps ever.
However, what is a problem though is that after adding the socket to the grip bone and choosing to add a preview of the weapon model results in the preview being ridiculously larger than it’s intended size. As to why is happening, I have no idea as I checked the original Blend file of the weapon to see if the scaling units were wrong or if the scaling hadn’t been applied, since that has caused me some problems in the past, but there didn’t seem to be any scaling issues that I could see. Moreover if I drag the weapon out directly into the level in Unreal Engine, the weapon appears at its proper size, so I not sure if the problem lies with the weapon model itself or if issue is restricted to the preview only.
I also tried shrinking the preview weapon but I could only shrink the weapon so far before it would disappear entirely, so that’s not really a solution either.
I only thing I’ve noticed out of ordinary that might be connected, is that after adding the socket to the “grip” bone, a large diamond-shaped outline larger than my character model appears, extending outwards from the location of the socket. I don’t know what diamond-shaped outline is, as it doesn’t appear in the video tutorial I’ve been using [Link: Sword Weapon Blueprint - #20 Creating A Role Playing Game With Unreal Engine 4 - YouTube]. Whether the diamond outline was perhaps something that was added to Unreal Engine in the subsequent two years after the video was originally posted or something else entirely, I don’t know.