The above scabbard appears to have crease marks where it may have been ritually folded as part of a votive deposit. Cf. V. Kruta et al. (eds.), The Celts, Venice, 1991, pp. 364-365 for bent swords and scabbards from a Celtic sanctuary at Gournay-sur-Aronde in France.
Also see V. Kruta op. cit., p. 567 for a detail of a scabbard top of similar shape. "The scabbard gave the craftsman a means of expressing great technical virtuosity ... The top of the sheath is always decorated, sometimes with cut sheet metal, sometimes with designs engraved with a burin, or by embossing or knurling."
For a similar scabbard with this type of opus-interrasile work in the Trier Museum, cf. Trier: Augustusstadt der Treverer, Mainz, 1984, pp. 93, pl. 4 and p. 289, no. 147.1, dated to 20 B.C.