I like the OP's "perfect fighting revolver". My perfect/ideal CCW revolver is close...
Medium frame, check. To me it is a draw between the K-frame for lighter weight, or an L-frame if it is the 7 shot 686 Plus for added capacity.
3" barrel, check.
DAO, I assume that's a check (I assume the bobbed hammer goes with a DAO conversion). To me this isn't 100% needed, but a somewhat bobbed hammer is needed for a smoother draw, though if left DA/SA I'd want some knurling/checkering cut into the top of the hammer.
Front night sight, check (though I'd accept a fiber optic)
I'd add a round butt and boot grips for easier concealment. I'd also want it bead blasted for a matte finish so it is less shiny in case my cover garment came uncovered to make it less noticeable.
I hadn't thought about the slab barrel, but it seems like a good idea to shave an ounce or two off, and if (as in his case) you had the barrel cut to 3" from a longer barrel it keeps things looking more professional than cut off make/model info would.
If I was going out and knowing/expecting there be a fight, and I was taking a revolver (I'd prefer a 12-15 round .40 or 9mm handgun, or even better, a carbine, in that situation) I'd bring a 4" barrel, 8-shot .357mag N-frame or a .41mag or .45LC 6-shot N-frame.