Typically used with: Agility.
In short: swiping and release. This skill isn't as nefarious as it sounds. Thievery represents the art of legerdemain, pilfering, and escape artistry. This skill can be used to draw a small weapon unnoticed, snatch an item away from a table, pick someone's pocket, and other movements that require the hand to be faster than the eye. It can also be used to slip out of tight bonds or another character's Grab.
It's like taking candy from a baby! Except a wallet is usually more valuable than candy. You can roll a Thievery check to deprive someone of their coin purse, swipe an object from a merchant stall, or slide the ring off the countess' finger, all without being noticed. The victim of the theft rolls a Perception check. If your Thievery check is higher, the item is yours. If their Perception check meets or exceeds your Thievery check, they immediately spot what you're doing and get a chance to hold onto the item. If you still want it, you can begin combat and make a Grip check to take it.
If the object is very small or otherwise easy to conceal (e.g. a marble, a dagger, four aces), you gain a +2 bonus on the Thievery check. If the object is large, heavy, or otherwise very noticeable (e.g. a Dachshund, an axe, a sack of potatoes, a longsword), you take a −4 penalty on the Thievery check.
You can use a Thievery check to knock the weapon out of someone's hand. Essentially, you're using your own weapon as a tool to swipe the other. Your opponent must roll a Grip check. See the "Disarming" entry in the Tactics section of Chapter 10: Combat. If your Thievery check beats their Grip check, you knock the weapon to the ground. Certain types of weapons, for instance whips and chains, grant a bonus to the Disarm check.
Escaping a Grab
You can roll a Thievery check to escape another creature's Grab. See the "Grabbing" entry in the Tactics section of Chapter 10: Combat. Using Thievery to escape from a Grab takes 3 AP. To try to pin you down, your opponent rolls a Grip check. If your Thievery check meets or exceeds their Grip, you're free of the Grab.
When you're trapped between a rock and a hard place, you can wriggle your way out. You could be wearing manacles, beneath a net, or stuck in a chimney. The tighter the hold on you or the more sophisticated the obstacle, the higher the DL to escape.
Any time you find yourself completely tied up, you gain the immobilized condition. The good news is that you can slip out of your rope bonds with a successful Thievery check. The better you're tied up, the higher the DL. In this case, the DL is taken from the Craft check of the character who tied you up.