What I just learned is that OE scīnan, to shine, gives OE scimrian, "to shine fitfully" [1]. Fascinating: Gothic skeima - torch, lantern.

[1] Eric Partridge: _Origins: A Short Etymological Dictionary of the English Language. sᴄᴇɴᴇ paragraphs 8,9.

Also fascinating: "prob from Old Norse skaerr" "is English sheer, bright, hence pure, hence sole, hence also transparent, perpendicular" under paragraph 10.

and further down the rabbit-hole, OHG filu-berht, full bright. Name of St. Philibert, "whose day falls on August 22 early in the nutting season". Norman French noix de filbert.