The name belongs to a number of warriors in Welsh legends, here are two of them.
Gweir
A warrior who was the son of Gairioedd.
He was imprisoned in Annwn, the Welsh Otherworld, and may have been rescued by Arthur.
Source
Preiddeu Annwfn | Attributed to Taliesin, c. 900
Gweir
One of Arthur’s warriors and advisors. His father was Gwestyl.
He was one of the three knights that Peredur saw as a youth, prompting him to begin his own career as a knight.
Sources
Breudwyt Rhonabwy | 13th century
Peredur | 13th century
Notes
Gweir, can mean ‘hay’, ‘collar’, ‘circle’, ‘loop’, or ‘bend’.
It may be the source of the Breton Guerec, or Erec, and may also be the origin of Gaheris.