You didn't give much info (tanto,katana,paracord,silk maki,etc.)If you are doing regular Tsuka-maki,the end shape easiest is a round radius.The hole should be about 5/16 to 3/8 inch.Look at some of the tutorials and see how to do it.Basically,once you reach the hole,you just keep going around the butt (assuming you have no kashira)and through the hole from both sides,until you meet in the center.A bamboo skewer is a good aid for pushing the maki through the hole.Use the blunt end,not the point.Keep everything flat and tight.When the whole end is covered,come out the hole and go back under the last wrap around the handle and cut the maki off.A dot of super glue will keep it from pulling back out.
Stacy