Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Vā̆sātes, um, and Vā̆sātae, ārum, m., a people of Aquitania, Aus. Parent. 24; Amm. 15, 11, 14.
Hence, Vā̆sātĭcus, a, um, adj., of or belonging to the Vasates: rheda, Aus. Ep. 7, 18.