98% of the sailboats out there have masts held up with steel cables and cable ends that are in effect half of a splice. My two small sailboats used cables with a breaking strength of 2000 lbs. Ends were made with standard telephone linesman nicro presses. Done right, there is absolutely no reason spices cannot be done on brake cables. But - that done right bit is important, even life-saving critical. Before I spliced a brake cable I would learn the breaking strength of a new cable and look up the strength of the slicing method. I would take real pains to do that splice right. And no, I have no idea what couplers are available for brake cable diameter cable. If it is 1/16" I believe there is a common nicropress sleeve and I think my press tool can do it. But I am guessing the brake cable is smaller and I wouldn't use an oversize sleeve! (Haven't thought about rigging a sailboat in many years. That phase of my life is done.)