Oh, he is good. Wait - 'Violation'? Violation of what? This bears some further scrutiny.
Terhune's broad smile returned as Will explained the modification he could make. The mystical obscurements he'd set up in his shoppe would fool any magical means of detection, at least while the item and inspector were in the building. The wards wouldn't help if they examined the item mystically once outside the shoppe, but he didn't intend to sell many "authentic magical artifacts" anyway (since doing so could very quickly draw the wrong kind of attention), just a few to those who seemed too gullible to bother mystically scanning it, too green to tell the difference between the magic of the item and the magic hiding the fact that the item was made very recently, or too desperate to care whether the item was three centuries or three weeks old.
He turned slightly to face Gwen, "oh, no, madame, no need for that: what your associate just described should be perfectly fine for my purposes. Now, is there anything you would be needing from me?"