ornament
珌 centers on a decorative ornament, specifically a jade or gemstone adornment used to embellish objects.
珌 combines 王 (jade) with 必, which likely contributes a phonetic element. The character refers to a jade ornament, consistent with the semantic component.
The left side 王 (jade) and right side 必 (certainly) suggest a piece of jade that is certainly an ornament. Picture a beautifully carved jade piece used to decorate a ceremonial object.
For ヒツ, imagine a jade ornament so precious it must be kept in a special hitsu (chest): hitsu -> ヒツ, and the ornament is safely stored inside.