Wait, Beherit, would this have something to do with the Behelit from Berserk?
Yes. In the book "The Lesser Key of Solomon" there are two demons which match the name: "Beleth" and "Behrit". Japanese people write in kanji and have problems in translating western names, and also switch the letters "R" and "L". I believe that Berith/Beherith/Beherith is the right one since it means "pact" in Hebrew language/Aramaic (often as a pact with God/s). It's super-obvious that Miura Kentaro made the Hand of God inspired by the Cenobites ("Monks") from the movie/s "Hellraiser". They serve Leviathan (a mythical creature) which later became a greater demon in grimoires (The Sacred magic of Abramelin the Mage). So it's not a coincidence at all that the amulet's name, Beherith, comes from a demon of another grimoire. The egg is a symbol of birth/rebirth, and the amulet works as a pact.
Curiosity: These grimoires are relatively moderns. They employ medieval titles (Duke, Marquis) which never existed in ancient times. Many demons (Baal, Amon, Astaroth/Ashtoreth, Haures) in reality are ancient gods from Akkadik and Egyptian pantheons, turned into demons by medieval (christian and hebrew) occultists.