Merchants of mammon: there are three TYPES of mammon NPC's. the Blacksmith of Mammon, the Merchant of Mammon, and Black Marketeer of Mammon.
Merchant of Mammon offers the player many different items in exchange for Ancient Adena (AA) which are obtained by converting Seal Stones through the Dawn/Dusk Priest of the winning side. The Merchant of Mammon offers Greater Dyes for tattooing, Enchant scrolls, Blessed resurrection/escape scrolls, among other things.
The Blacksmith of Mammon will aid in the sealing/unsealing of A grade armor and up, will manufacture A grade weaponry and above, will hot-swap D grade weaponry based on Crystal count as well as C grade weaponry. He will also allow you to Upgrade your D weapon from lowest item level all the way through to top C Weaponry in increments asking ancient adena for his services.
The Black Marketeer of Mammon will allow you to purchase a limited amount of items for ancient adena, and will trade Ancient adena for regular adena at a rate of 1:1 which for most players is a complete rip-off. He also removes Special Abilities from C grade and above weaponry for a fee in Ancient Adena.
Merchant and blacksmith travel through Necropolii and Catacombs (respectively) during the SEAL VALIDATION PERIOD where the seals of Avarice and gnosis have been broken. Breaking Avarice releases the Merchant of mammon into necropolii, and gnosis the blacksmith into catacombs.