I have many dog-bone sharpeners scattered throughout my kits. ( Lansky Triangle ,4" or so long.) I tossed ALL my ends in the trash. First they suck as angle guides , and second , limit the usable length of the rod. I rounded the ends a little bit with a diamond stone ( since they are hard ceramic) to make them more pocket-friendly , and now they slide easily into any pouch or pocket.
I almost always sharpen with a stationary knife and move my sharpening medium ( in this case, the ceramic triangle) and get excellent edge control and full use of the stone as I just flip it over once in a while.
Never did like the concept of moving a knife over a stone that's smaller than the blade , but I have no problem sharpening large blades with a 3-4" stone ,moving along the edge. Plus, they're always handy to carry. :thumbup: