This skill is usually practiced by simple manual dexterity and swiftness. Even so, there is a small number of simple items which can help the thief in this art.
Arm Sling[]
This is simply a cloth sling; the thief wears it to appear as if he has a broken or injured arm, and speedily withdraws his hand from it for the pocket-picking attempt.
This actually reduces the chances of picking pockets by 5%, but the payoff is that the chances for being discovered are halved (but a natural 00 on d100 always means discovery). This reflects the fact that people simply do not expect to see a man with a broken arm picking pockets and the expectation determines the perception. The use of this unusual strategy is only useful—but it is really useful here—when the priority is not to be discovered, rather than to be sure of success. A thief working in a city where he is not a guild member, or one where legal penalties for picking pockets are very harsh, might favor the use of this ruse.
A thief obviously cannot use this ruse for an extended period of time in the same place (save possibly by posing as a beggar). There is a limit to how long an arm can plausibly need for healing, after all.
Mini-Blade[]
This is a generic term for a very small (and usually very sharp) blade which can be held (with care!) between the fingers or in the "edge of the hand". A very sharp coin-edge, filed down, can be used in this way, and has the advantage of being readily available. A more sophisticated (and rarer) version is the razor ring, a hollow signet ring with a flip-top and a very sharp blade within.
The mini-blade is used to cut a soft container—most obviously a purse or pouch—so that the thief can get at what's inside it. It is the most effective technique for getting at coins, gems, etc., inside a purse with drawn and tied strings. With a mini-blade the thief only has to make a simple pick pockets roll to effect the larceny. If the thief has, instead, to try to open the purse strings and then extract what's inside because he has no mini-blade, this needs two pick pockets rolls for success (one to open the purse, one to get at the goodies)—and two rolls for being observed, as well!