Gender is usually masc. when used of the Holy Spirit (as well as evil spirits!) in later Syriac texts. (On this see now J. W. Childers, "Patristic Citations and Versional Evidence: The Syriac Version(s) of Chrysostom's Homilies on Matthew and the Old Syriac Text", Le Muséon 115[2002]p. 135.) In early texts the holy spirit is femine, however; see, e.g., D.J. Taylor, CSCO 577 (1999) p. xxi; and the complete discussion in S. Brock, Aram 3(1991): 249ff. Also masculine in CPA.
For all the functionality of this word in Syriac scripture see the extensive discussion in IshGen 112f.