I had this situation come up over weekend and I ruled against it. Does anyone have some advice on this?
There is no reason to think the weapon 'teleports' but it isn't really in a particular position anyway. It just attacks a designated target, within medium range of you and the attacks come from your direction. So if they take a short range teleport, are still in range and visible to you, your weapon will continue to attack them without you having to redirect it. In a sense, this might seem like the weapon is teleportating with them, but it isn't really any different than if the target just moved the same distance via mundane means.
Thanks for the response, Dave.