Agent can disguise in many professions and like that he can use items that belong to those professions. Maybe he is successfully coning you, because he has this option that is not available to the others. But in time you will get to know how to recognize the disguised agent and you will be able to fight him back. It would help if your character is more offensive then defensive. Let say that you are Shade I, than you will not have any problem. Even if you do, that is part of the game and it wouldnt be half the fun if you are able to protect yourself from everything.