Herbert

"radiating or reflecting light," Old English bryht, metathesis of beorht "bright; splendid; clear-sounding; beautiful; divine," from Proto-Germanic *berhtaz "bright" (source also of Old Saxon berht, Old Norse bjartr, Old High German beraht, Gothic bairhts "bright"), from PIE root *bhereg- "to shine; bright, white." The meaning "quick-witted, having brilliant mental qualities" is from 1741.

The Germanic word was commonly used to form given names, and figures in the etymology of Robert, Albert, Bertha, Egbert, Gilbert, Herbert, Hubert, Lambert. In modern German it survives in names only (Albrecht, Ruprecht) and has been otherwise lost.

Old English hergian "make war, lay waste, ravage, plunder," the word used in the Anglo-Saxon Chronicle for what the Vikings did to England, from Proto-Germanic *harjon (source also of Old Frisian urheria "lay waste, ravage, plunder," Old Norse herja "to make a raid, to plunder," Old Saxon and Old High German herion, German verheeren "to destroy, lay waste, devastate"). This is literally "to overrun with an army," from Proto-Germanic *harjan "an armed force" (source also of Old English here, Old Norse herr "crowd, great number; army, troop," Old Saxon and Old Frisian heri, Dutch heir, Old High German har, German Heer, Gothic harjis "a host, army").

The Germanic words come from PIE root *korio- "war" also "war-band, host, army" (source also of Lithuanian karas "war, quarrel," karias "host, army;" Old Church Slavonic kara "strife;" Middle Irish cuire "troop;" Old Persian kara "host, people, army;" Greek koiranos "ruler, leader, commander"). Weakened sense of "worry, goad, harass" is from c. 1400. Related: Harried; harrying.

*bherəg-, Proto-Indo-European root meaning "to shine; bright, white." It forms all or part of: Albert; Bertha; birch; bright; Egbert; Ethelbert; Gilbert; Herbert; Hubert; Lambert; Robert.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhrajate "shines, glitters;" Lithuanian brėkšti "to dawn;" Welsh berth "bright, beautiful."