During the last few months the ebony handle on my Tanaka gyuto has developed an 1.5 inch long crack from the ferrule. Is there anything that can be done? Will soaking in mineral oil, or simmering in water help? Or do I fill is with wood putty? Cut my losses and get it rehandled? Are hardwoods more prone to cracking that the ho, keyaki and burnt chestnut handles of my other knives? Of all of my wa handles, this it the only one to crack. Has it reached a point of no return, a harbinger of the handle splitting to a level of discomfort? I'm a lefty, so the crack is situated where I place my thumb.