You can get Barge cement at the local Hobby Lobby, it is made for leather.
I glue my leather handles on and don't stitch them. I have a tutorial on this site somewhere about how to get a perfect fit. It would be easy to glue on the leather and stich it on after the fact.
I checked and my tutorial on leather handles was on the Trad Gang, they tossed me off the site for telling them the truth about a member who they thought was advertising his archery tournament for free on the Trad Gang and charging many of the Trad Gang sponsors to set up at his tournaments. I knew Terry never charged the companies a dime to set up at his tournaments. The tossed me, deleted at least a have a dozen of my very involved tutorials, found out I was right and let me back in but my tutorials were apparently in outer space never to return.