Dictionary of Medieval Names
from European Sources

Bertwin m. Old High German beraht, Old Saxon berht 'bright' from Proto-Germanic *berhtaz + Old High German wini 'friend'.

Cf. Winebert.

France
Latin
c823 Bertoinus (nom) irminon-vol2 21, Gaugiacum
Cite as: S.L. Uckelman. "Bertwin". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2017, no. 1. http://dmnes.org/2017/1/name/Bertwin.