Early postglacial decorated finds from dredged river beds have been recognized in the northern France during the last century. They concern several engraved pieces made from Red deer antler. The technological investigation presented in this paper demonstrates the finds were used as tools carrying symbolic value. Engraved and bind before use, the peculiar engraved motive they display was not intended to be visible at the time the tools were employed for heavy duty purpose. In the form of a registry of geometric patterns carefully drilled on the body of the tool, and arranged symmetrically compared to its shaft, the motive yielded by the engravings themselves shows the art was made to adorn the tool, but not only. The paper discusses the magic function of this art seen as a hidden symbolism used for arming certain tools, making them amongst all other of the kind however left unengraved, specific to a particular use. Other heavy-duty tools showing a similar art-form, actually deriving from more recent and securely dated archaeological contexts, are also illustrated for a relative dating of these finds.