Take a look at the handle core in the photos of the sword build I have up right now. You will see the handle is inlet the thickness of the rayskin plus the wrap. This keeps the cord/wrap locked tight in use.
The best way to make the handle strong and secure is to epoxy it when the wrap is done. Check it over carefully, and make sure all is right. Re-wrap if needed until you get it perfect. Then mix up some thin and slow cure epoxy. I like System Three Clear Coat, but West System 105 resin with the 206 or 207 hardener is also good.
Paint it on with a small flux brush ( cut the bristles about 1/4" long) an paint the resin on lightly. You just want to see a sheen on the wrap. It will soak in almost immediately....which is what you want. It should not look wet after a few minutes. Take an old tee shirt or lint free cloth and squeeze the handle if you think there is too much resin. Brush again with a dry brush, and let sit to cure. rotate every 10-20 minutes and check for any drips. Any excess or drips can be removed with denatured alcohol before curing. Once set, let cure 24 hours.
