Properly spliced, your handle is actually stronger than a single stock handle. But if you're worried about cutting into the splice just use the spliced end that has the most "meat" on it for shaping your rest/shelf.
To retain the most gluing surface, only splice your handle width, not bow width. For example: if you handle is 1" to 1 1/4" wide, then only lay your splice out for that. But if you're building a board bow where you're adding a handle piece/backing then doing a bow width splice is acceptable........ART