Ægishjalmur / Helm of Awe is a symbol from norse mythology.
Knitted from the top.
Available in English and Norwegian.

“The Runegalder symbol Ægishjálmur from Galdrabók is also called the “Helmet of Terror”. The rune gilder, which consists of eight of the Viking Age’s m-runes or Old Norse r-runes, rotating around a central point, was used for incantations and as protection. It should both create terror in the enemy and strengthen one’s own power.“

(Translated from: https://www.gyldendal.no/artikler/de-magiske-runesymbolene/)