John, you’re right, Leica do say that, but surely it must be a mistake? Leica isn’t known for the accuracy of their published technical specifications.........
Edit: The 10x32 is slightly heavier than the 8x32, as would be expected, at 565 and 535 grams respectively, but in any event the 7x42 must be the lightest of the three 42mm's because it has fewer glass elements than the 8x and 10x.
Mike and John, if I am understanding your gist correctly it does happen that 10s can weigh less than 8s. For instance my Swarovski SLC 10x42 is shorter than and lighter than the 8x version. To do with the eyepieces I am told.