Hmmm. Thought I responded to this thread, but the post never appeared. Strange. Anyway...
I believe the now-discontinued S&W model 337PD is the lightest +P-rated revolver ever made in .38 Special, edging the other competitors out by weighing-in at 10.7 ounces. I owned one of these for several years, and while it worked like a dream for drop-in-the-pocket carry duties, it was NOT very pleasant to shoot, even using low-powered target ammo.
You can see the "+P Jacketed" warning on the barrel; apparently, lead bullets wouldn't stay put in the cases during recoil, so using jacketed bullets was required to prevent bullets from creeping forward and jamming the cylinder. I never had any problems with mine, but I usually default to jacketed bullets for defensive use anyway.