The primary headword is only attested here and in other lexica and grammars (e.g. Zonaras 1640.5, Gennadius Scholarius 2.484.15), and is probably a mistake (rather than a plausible variant) for sh/kasqen, aorist passive indicative, third person plural (epic dialect), of the hypothetical verb *shka/zw (see n. 1 below).
For related words see the next four entries, sigma 300 through sigma 303.
[1] From commentary to Homer, Iliad 8.131, the only literary attestation of sh/kasqen (see general note above); cf. the scholia there; Apollonius Sophistes, Homeric Lexicon 141.8 (s.v. shko/s); Etymologicum Magnum 711.3; Hesychius sigma479. Adler also cites Lexicon Ambrosianum 291.
[2] Aorist passive participle, accusative plural masculine, of the same verb; attested only here and in the quotation that follows, from which it is presumably extracted.
[3] Quotation unidentifiable. Adler suggests Aelian (via the Excerpta of Constantine Porphyrogenitus) as a possible source. Possibly also from a paraphrase or commentary on Xenophon, Cyropaedeia 3.3.63-70.
[4] Greek Anthology 6.219.1 (attributed to Antipater of Sidon). There is no obvious connection between this quotation and the rest of the entry. As Küster suggested, it may have been displaced from an entry on the participle sesobh/menos ('agitated'); cf. sigma 265. Additional extracts from Greek Anthology 6.219 may be found at alpha 1510, alpha 1828, alpha 4172, epsilon 747, zeta 19, kappa 2544, lambda 869, and sigma 1723.