diviner, medium
覡 centers on a person who acts as a bridge to spirits or the divine: a diviner or medium who sees what is hidden.
覡 combines 巫 (shaman, medium) and 見 (see), suggesting a shaman who sees spirits or the unseen. The exact historical development is uncertain, but the component relationship is clear.
A shaman 巫 uses their sight 見 to peer into the spirit world, acting as a diviner or medium.
For ゲキ, imagine a medium struck by a sudden vision with a sharp 'geki!' sound, like a dramatic revelation.