First of all, it's not the original "power" & "Vanquishing" weapons. Those are just normal weapons now.
The ones that the NPC takes have the Power, Vanquishing or Mystic label on them, and were special loot from a number of the invasions fo the last few years. Specifically, the Britain Invasion of Spring 2005, the Ophidian Invasion of Summer 2006, and the destruction of Magincia in Fall 2007.
The Ophidians (not orphain) had some stuff on the remaining red ones from 2006 (which some shards still had in the lower level of Terethan Keep in T2A, as recently as a couple months ago, but most finally got cleared by people looking for items to turn in). If any remain, they are probably in the Felucca T2A keeps. (the weapons were on generals, the snake skins on the plain snakes, and the orders, rations and journals on lesser rank ophidians)
However, when the turn-ins were announced, they changed the snake skins and Ophidian rations to now be part of the loot of the normal Ophidians in T2A (of any type). The ratio appears to be about 1 skin for every 20 to 30 rations. The rations look like gray food, and you want to make sure you turn in the food one item at a time (you will only get one item's points for turning in a stack of 2-9)