Ingwaz
The God Who Went East
What the one gloss records is a leaving; fertility readings come from Freyr's cult, not these six lines.
The Younger Futhark had no ng-rune, so the Old English poem is the only medieval gloss: Ing was first seen by men among the East Danes, until he departed eastwards over the wave with his wagon running behind him, and so the Heardingas named the hero. The poem calls Ing a hero rather than a god. The identification with Yngvi-Freyr is scholarly inference drawn from the dynastic name Ynglingar and from the Ingaevones Tacitus lists in 98, and it is inference worth stating as such. The letter has two attested shapes, the plain lozenge and the lozenge raised on two staves. Fertility readings come from Freyr's recorded cult, not from these six lines.
Light
An arrival worth remembering. A people saw this figure first, kept his name afterwards, and the departure eastward over the water is told as procession rather than as loss.
Shadow
What the single gloss actually records is a leaving. Ing goes and does not come back, and almost everything else attached to this letter is later inference stacked on six lines.