The S&W 3913 doesn't meet my guidelines, and isn't in production. Unless you mean to say you'd like an altered version of it which meets the guidelines of the original post, saying it's perfect as an answer to the question here is a non sequitur.
Yes, it's thin, and probably feels thin enough to satisfy me. Yes, it is a traditional double action.
However, to my knowledge, it didn't come in a decocker-only version. It didn't have a version which weighed less than 20 ounces. Another important quality which wasn't a bullet point, but was part of my framing of the question is that a pistol meeting these criteria be in production. This is important because one of the reasons I lament this gap in available pistols is that I would recommend such a pistol to some of my friends and acquaintances(if it had a reasonable record of reliability too, of course.) I rarely, if ever, give a strong recommendation for any piece of equipment which is out of production, for several reasons. I sometimes give mild recommendations to out of production tools, but such recommendations always come with an explicit caveat that I don't know if one might be able to easily find the tool for sale, and that service and parts may be expensive and/or difficult to obtain.
That is not to say I don't value out of production tools myself for various reasons, but I do think that being out of production limits the usefulness of a tool. I like my primary tools to be ones I'm willing to replace. If replacement is difficult, I'm less likely to consider a tool for regular use, and even less likely to recommend it as a primary option.