What does Pickpocketing : Perfect Touch do?

The perk allows you to can pickpocket equipped items, like armor.

You can use it along with Misdirection to strip/gain a tactical advantage against a NPC (like Astrid) before you engage in combat with them. The can be useful with followers as well. Sometimes followers will refuse to equip the items you give them. You can use these two perks to pickpocket the items you wish to replace with the improved items. They also helps with NPCs who will not trade their equipped items with you.

You can now pickpocket all equipped items from a character.

Keep in mind that you need to remain hidden from that character (other people noticing you is fine), and also, some characters with unique/special armor (like for instance, Ulfric) can't have their equipment stolen.

To test to make sure it's working, find a regular guard in any town, and while remaining hidden from them, try to pick their pocket. You should find lots of armor with little triangles to the left (to show they're equipped).