Can't make my friends knives sharp

I’ll take a stab at your problem, just bear in mind that this is my personal opinion and there may be better solutions.

First of all VG10 ans SG2 are very different alloys from the softer stainless steels in most Victorinox knives; in other words the Victorinox needs a steeper (or more acute) angle to stay reasonably sharp and functional.  What you have done with the 15 degrees per side hasn’t hurt anything and may have actually thinned the cross section so that less effort will be needed to cut or slice.  The problem is that the softer steel won’t keep the edge you have so painstakingly tried to give it even through the sharpening process and certainly won’t hold up to to actually cutting much of anything.

I’m assuming that your diamond and ceramic stones are broken in; that is they don’t leave scratches much larger or deeper than they are supposed to.  The simple solution is to take your 15 degree fine edge and put a micro bevel at about 22 degrees per side with a diamond stone using very light strokes at close to perpendicular to the edge (not sweeping strokes) which will give the knife some tooth and resistance to the edge rolling over.  I would start with 800 grit diamond and use some water with a little detergent on the stone to help lubricate and wash away the swarf.  You may want to experiment with grit and angle a bit depending on how the knife is used and who is using it. The micro bevel you want should be barely perceptible to the naked eye, but wide enough to keep the edge from rolling over and making a wire edge.  Search this forum for  micro bevel, wire edge and obtaining a burr and you will have a better understanding of some of what is involved.

Remember to use light strokes and let the grit do the work; diamonds are not forever and pushing them too hard causes them to wear out prematurely but more important it causes the diamond particles to push metal much the same way a bulldozer pushes dirt leaving behind a weakened substrate and not lifting away all of the metal you really want to remove.

True sharpness is totally dependent on blade metallurgy, heat treating, who is using the knife, what they are cutting and their expectations of edge longevity.  There is no magic one fits all solution.

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Gregg776 wrote:

Remember to use light strokes and let the grit do the work;

I would print that words in bold in capital letters and put on a big banner on the wall. For microbevel it is critical that you should not apply any pressure. Microbevel is not visible to naked eye, it is very tiny. If you apply pressure, you will ruin it. Also you make only a few stokes, do not make many strokes. Microbevel is an art of its own.