Quartermaster Ival at Mellaggan’s Valor waypoint allows you to hand in as many items as you want to get provisioner tokens. Essentially handing in an item to him makes Steward Katren at Faren’s Flyer waypoint think you’ve already handed a weapon to her and also therefore means that you can keep handing in items to Ival. For purposes of investigation I used Apothecary’s Noble Shoulders as the hand in item to Ival.
There has also been a case in the past where a friend reported the same issue between Westwatch and Southwatch provisioners respectively but that has subsequently been fixed. I am unsure about the others but it is worth checking out as I have only ever handed in the items in a particular order (hence doing a different order could reveal the same issue between other provisioners).