The Gué-de-Velluire sword (Vendée, France) is part of the Rochebrune collection collected during the 19 th and the 20 th centuries and now preserved in the Dobrée Museum in Nantes (Loire-Atlantique, France). The unusual shape of its hilt, its uncorroded rivets and the rather uncommon combination of a bronze grip with an iron blade made this sword an exceptional object. It has been depicted in a large number of papers since the 20 th century, but the question of its authenticity has hardly ever been tackled. New analyses performed with the support of the Dobrée Museum, the Arc'Antique laboratory and Ghent University delivered new data enabling us to discuss this delicate question. First, a CT-scan of the sword was performed by the BCRX company (Mordelles, Ille-et-Vilaine, France), offering the opportunity to visualise the inner structure of the hilt and especially the way it is fixed to the iron blade. Secondly, X-Ray Fluorescence analyses were performed by the Arc'Antique laboratory (Nantes, Loire-Atlantique, France) to determine the composition of the different parts of the sword (hilt, rivets and blade). Comparing the results of both analyses with Rochebrune's archives allowed us to assert this weapon is a fake, most likely consisting of two authentic archaeological artefacts, and to reconstruct its production process, shedding light on early 20 th century collector's practices.