Most folks use a screwdriver or similar tool and transfer the epoyx a little at a time. If you are using slow set epoxy, time is not an issue. Let the epoxy slide down one side of the hole. Don't put in too much at a time, and tilt the handle at about 75 degrees, or it will make a vapor lock and none of the epoxy will slide down until the bubble pops.
Now, that works OK, but here is a trick I use that makes it a snap. Put a coffee stir down the hole - one with a hole down the center, like a tiny straw. Now you can pour the epoxy in in a steady stream from a small cup and it will slide down the hole as the air escapes back up the straw. When the hole is filled, slowly lift out the straw and put the tang in the hole.....viola!...completley filled hole.
Now, for an added tip ( two for one tonight);
The end of the handle block needs to fit flat against the guard to avoid a gap on one side or another. This can drive you nuts as you sand a little here and then find a gap on the other side. What you do is chamfer the tang hole out toward the edge until it has about an 1/8" flat edge around the perimeter. Now you can easily sand/file the high spots until the handle and guard fit perfect. The same technique works well on butt caps.
