The Ancient Seal is one of the many monster drops that can be acquired in the Frontier. They are typically acquired as a possible drop from the Blueman, a hostile tribe found in Frigid Waste (PvP).
As its description implies, the Ancient Seal is a wood and stone seal with an odd engraving. The odd engraving closely resembles the 'Safe Zones rock.' Other than that, not much can be said about its overall appearance.
The Ancient Seal does not have any apparent usages in-game, other than being sold to a selling vendor at a selling price of 4,000 gold.