Add another toggle at the wire s upper end, particularly on stays with sails hanked to them, as these are most heavily worked. Toggles are a great investment to prolong the life of your rigging. Swages are the overwhelmingly favorite choice for sailboat terminals because of their low cost, neat, compact appearance and high initial tensile strength. But they are not to be trusted. When swages fatigue, they ll crack, too.
Cracked swages can survive for years or days.
Replace any wire that has a cracked swage on it immediately, unless you enjoy that sort of gamble. A horizontal crack is always more dangerous than a vertical one. Use a magnifying glass or dye penetrant to spot fine cracks. Check the eye as well as the barrel of the fitting. To maximize swage and wire life, consider inverting each wire when you figure it has reached its half-life, before cracks appear.