This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
珴 is a rare character combining 王 (jade) with 我 as a phonetic component. Its exact historical development is uncertain.
The left side 王 suggests jade or a precious stone, and the right side 我 looks like a weapon. Picture a rare jade artifact shaped like a halberd, but its true meaning is unclear.
For ガ, imagine a guard (ガード) protecting a rare jade piece: guard -> ガ, and the jade 王 is guarded by the 我 shape.