I've got two large regular Sebenzas in my collection and upon closer inspection I noticed one of them having grooves on the outer rim of the handle whereas the other doesn't have them. Is there any reason for this or was it simply a change in the design? Do the grooves resemble a certain production period? Or is it possible that the one is featured on BG-42 and the other on S30V knives? Thanks a lot for your time!