The base problem is not who where and when , players tried to use the NPC and it was bugged took items from players and didnt perform the required instruction hence Bugged.
many features of the game tend from time to time have these querks , but when things like a specialised NPC is bugged and after fix you can no longer use it then it does lead to fustration . That aside I do think a Event NPC for amulet salvs would be a good idea as lets face it the owner of SW makes money from its own troops using it as it is now.
If the event NPC was placed in SW outside or in a shop within SW then that holding guild would have that income aswell.......