|Ok, aside from the fact that some people have macroes set to yell "Guards", you should get away with this with no problem. It is a combination of using crates or other objects you cannot walk through as well as the "granite chair" bug.. ok. what you do is go to any moongate of your choice. (Preferrably one with more people coming in then standing around by you) Then place four crates or legs or any other object that you cannot walk through. Now, pick up the lower right one, (most people try to pick this up first) now, walk to the spot and drop on your spell book. Since it wont work, it puts it back down with you standing on it. Now hide. When someone comes through, they cannot move. They pick up the chest and since most people comming through gates have lost stamina, they cannot get by you. Meanwhile, you are choosing what you want! Steal it and run. You have about 2-3 seconds after you leave the circle of gate rocks before the massage "Guards can no longer be called on you" then just hide again and enjoy your new silver vanquishing katana!
This works best when a tamer comes thru with like 10 mares and cannot see the moongate to double click and is frantically trying to figure out what to do. Also, try bringing some friends to stand on other items just in case they go up or left.