Case steel can be pretty finicky.
Once I get a burr on both sides I go to almost no pressure on the stones.
It doesn’t take much pressure to remove steel from such a small blade.
Also I never used diamond plates on Case steel, neither CV or the stainless, they are way too aggressive.
The key with using a diamond hone on small knives in such steel is to downsize the grit used and the pressure applied, for the task. Scale the grit, pressure and number of passes to the job at hand, i.e., blade size, thickness, steel type. A Fine (600) diamond hone can do anything that's needed, from reprofiling to touching up, with much less effort (pressure and number of passes). Anything coarser than the 600 diamond would be overkill, unless the blade is large and/or very thick, and it leaves the edge on a small blade too ragged to be very useful, without more refinement at a finer grit. And for touching up, just a handful of
very light passes (maybe 3 - 10) per side, on a Fine or EF diamond hone, can do all that's needed.
Many will overgrind with a diamond hone, counting a certain number of passes or going a given length of time before assuming it's 'done'. Or, they'll start at too-coarse a grit. Since a diamond hone can work at 2X - 3X the pace of other stones at a similar grit, it's important to watch closely for the apex with every pass, which will come a lot faster, especially on a very small blade like the Peanut's. On a blade that small, sharpening with a bench-sized (6"/8") 'Fine' diamond hone could get it there in perhaps 5 passes or less per side, completely resetting the bevels.
So, 'too aggressive' comes down to either (1) too-coarse a grit for the job, or (2) grinding too long or with too much pressure for the steel type/thickness/hardness being sharpened. The abrasive type, by itself, doesn't matter as much, so long as it's hard enough to cut the steel being sharpened. The extreme hardness of diamond for cutting these steels is a good thing, because it means it cuts the steel very cleanly and effortlessly at a
light touch (this is all-important), which minimizes burring.
I'm not real crazy about rod-type diamond hones, as many of them, including the SM's diamond rods, are maybe a little too coarse for small(ish) blades in simple steels. The SM's diamond rods have been characterized at around ~ 400-grit. If using them, I'd limit such work to only the flats of triangular rods, as the corners focus too much pressure to be managed easily, with diamond in particular. I set my lowest-grit threshold for such small blades & steels at something equivalent to DMT's Fine (600) hone, which leaves the edge much cleaner & sharper, with less work.
