The headword, presumably extracted from the quotation given, is the aorist active participle, masculine accusative singular (and neuter nominative/accusative plural) of the verb sxa/zw, I lance, slit open (in order to let something escape); cf. sigma 1768 and see generally LSJ s.v.
[1] The gloss is the same form as the lemma, but from the verb te/mnw, I cut; cf. tau 299, tau 300, tau 301, alpha 1030 (gloss), and see generally LSJ s.v.
[2] Arrian, Fragmenta incerta [from the Parthica or the History of Alexander's Successors] fr. 26 Roos (p. 290), = FGrH 156 F168, for which Adler cites the Excerpta Constantini Porphyrogeniti; cf. de Boor, p. 28. [In her critical apparatus Adler reports that ms G omits ou(/tws (thus).]