From ek and astrapto; to lighten forth, i.e. (figuratively) to be radiant (of very white garments) -- glistening.
see GREEK ek
see GREEK astrapto
1. properly, to send forth lightning, to lighten.
2. to flash out like lightning, to shine, be radiant: of garments, Luke 9:29; (of gleaming arms, Nahum 3:3; Ezekiel 1:4, 7; φόβῳ καί κάλλει πολλῷ Tryphiodor. 103; (cf. Winer's Grammar, 102 (97))).