Smith & Wesson 642...
• .38 Special, decent defensive caliber
• Super lightweight & compact, carry all day
• Stainless can stand up to sweat/moisture better than blue steel.
• Double-action only, so easy to extract quickly (no hammer spur, no snags)
• Only one way to fire, simple and safe
• Crimson Trace grips are a nice touch, but regular practice is even better
• Suggest 148g wadcutter loads for a good compromise between effective defensive load and something controllable you can practice with dozens of rounds.
S&W Model 642