These arrows were sold by Andormu and Nozari in Caverns of Time for 2File:Gold.png. You had to be honored with the The Scale of the Sands to purchase these arrows. There are also ammunition vendors on both Scryer Tier and Aldor Rise occupying a previously uninhabited building on the right side of each camp (as viewed from the Terrace of Light). These vendors sell all ammunition from Blackflight Arrows and up (with the exception of the Halaa ammunition and the crafted Adamantite Stingers). You must have the required reputation with their respective sources to buy a given ammunition type from these vendors.