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I think the thickness together with the way the grain is running is your problem here. If you have some more cut in the same way then you might want to try adding a liner such as wenge veneer - where the linear grain will add strength - you will still need to thin the existing stock though.
I've used this successfully on a few razors including one in maple burr where the contrast in colours looks really nice.
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If you have not thrown the out and if you can free them.
You can epoxy them back together and embed wire to the inside of the sanded scales to re-enforce the area and still use them, they took my breath away it would be a shame not to use them.
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The cross cut makes them inherently weak. I think it was Harrywally who suggested backing this type of material with a veneer running in the other direction, eg, lengthwise. A local boat builder also showed me how to steam timber, which makes it more supple. A fairly simple process. Like UKRob suggested, thinner stock may help also.Best of luck.