The description of the amulet (you

The description of the amulet (you can see it in your inventory in-game) states something like "this amulet was given to me by the mages" which refers to the point in game when one of the mages gives this amulet to the player if the player joined the Mages. But the player is not given this amulet if he does not join the Mages. So either the description on the amulet is incorrect or the amulet was meant to be received only when the player joined Mages. Considering that Mages armor has lower defense stats then the armors of other factions the amulet was probably meant exclusively for the Mages faction (as the additional protection to bring the total defense for the Mages on par with what player can get with other factions). This is why I opted out to consider amulet description correct but the fact that amulet was on sale and available for other factions - a bug.