[1] The headword and glossing phrase derive from the Synagoge sigma39 (Cunningham), which is also the source for Photius, Lexicon s.v. (Porson 503.25, now sigma115 Theodoridis -- with, to be sure, a slightly different gloss: leptoi=s i(ma=sin). See similarly Hesychius sigma337 (Hansen). The headword is the dative plural of the feminine noun seira/ (sigma 274). This form does not occur in the quotation given here and must be extracted from another source: extant possibilities are numerous, but a likely one (championed by Theodoridis) is Proverbs 5.22 LXX, which generated patristic comment.
[2] A conjectured fragment of Arrian's Parthica (fr. 20 Roos). Greek and Roman authors report the military use of lassos among nomadic pastoralists of the Steppe, including the Sarmatians (e.g. Herodotus 7.85; Pomponius Mela 1.114; Pausanias 1.21.5) and Alans (Josephus, Jewish War 7.7.4 [250]). The application of the adjective seirofo/ros, "lasso-carrying", to the Parthians is unique to this entry. See sigma 287 for an alternative context.