The headword adjective occurs in Homer, Hesiod, and other early poets. (Later it is rare, generally referring to Homeric and Hesiodic passages; only Maximus Astrologus and Nonnus seem to use it in a original way.)
As to the glosses, they seem to have a double source:
(i) Probably via Hesychius s.v., the scholia to Homer, Iliad 20.154: dushlege/os: deinou=, duskolou=, xalepou= (scholia vetera and scholia recentiora) -- which explains xalepo/s here.
(ii) The scholia to Hesiod, Theogony 652: dushlege/os: dusfronti/stou, duseklu/tou, kakoh/xou (scholia vetera Di Gregorio), which explains kako/hxos.
[1] Meaning according to LSJ. The sense, in this context (in relation to the Hesiodic verse), is perhaps "bringing a sentiment of uneasiness, disquieting". For a more straightforward application see under delta 1634.