For a mid-size, I would go with a GLOCK 42. I carry one off duty and gave one to my wife who has problems handling a heavier gun or working the slide. It is 100 % reliable and shoots as well as a larger gun.
I could also recommend the WALTHER PPK (not the PPK/S which will kick harder due to the squared off grip in the web of the hand area). The PPK is harder to conceal than the GLOCK 42 and may not be as reliable, though my experience with the PPK has been excellent.
The larger PP series is too hard to conceal and kicks harder than the PPK in my opinion.
The SIG 232 is the best of the PP styled .380ACP pistols that I have shot. It has the best grip ergonomics for me in the base, blue alloy frame gun with very good trigger, SIG thumb decocker, great reliability and very good sights.
It is light enough for a pocket carry, but to bulky. I tried it and gave up.
The BERETTA Cheetah series, model 84 (13 shot magazine capacity) and 85 (8 shot magazine) are LARGE .380ACP pistols, as big and heavy as many mid size 9m.m. pistols. The good points are reliability (it may be the most reliable .380ACP pistol), good ergonomics, mild recoil (due to weight and large grip area), good sights, decocking safety on newer models and accurates. They are just as hard to conceal as a GLOCK 19.
Some earlier guns had positive traits for a pocket pistol.
The BROWNING/FN 1910/1955 was a great pocket gun to carry. It was light, very slim and had sights that would never hang up. Down side is the single action trigger and small controls, which disqualifies it as a pocket gun for me. I would have carried it with a full mag and chamber empty in a pocket holster. Also, very SMALL sights. Overall, the best pocket gun available till the WALTHER PPK was introduced.
COLT 1908, it was called the POCKET HAMMERLESS, but you would need a really large pocket for this one and suspenders as well. It was all steel, big as the GLOCK 19 and heavy, with small sights and single action trigger. It was also very reliable, easy to shoot due to the large grip, had mild recoil and was quite slim. It was another gun I would have carried with the chamber empty.
Both of these guns had grip safety's.
COLT reintroduced a .380ACP pistol in 1984. It was completely different from the 1908, except for caliber and size. It was a miniature 1911, with a locked breech, steel frame, single action trigger, 1911 style safety on the left side where the thumb can snap it off and good sights. Then they offered a lightweight version with an alloy frame. Then the smaller Mustang with shorter barrel, slide and grip. The Mustang has been put back into production in both a metal framed and plastic framed versions.
They have the same problems as the 1908 had, namely a 1911 style, single action trigger. This might not be a negative for some, but rules it out for my use.
Jim