{Coming down out of heaven} (katabainonta ek tou ouranou).
Present active predicate participle. Not the angel of  17:1,7,15 
(John's guide), but one announcing the doom of Babylon (Rome). As
in  10:1  20:1 . {Was lightened} (eph(9374)isth(885c)). First aorist
passive of ph(9374)iz(935c), old causative verb (from ph(9373), light),
common in N.T. as in  Re 18:1  21:23  22:5 . {With his glory}
(ek t(8873) dox(8873) autou). "By reason of (ek as in  8:13  16:10 )
his glory." "So recently has he come from the Presence that in
passing he flings a broad belt of light across the dark earth"
(Swete).