Doesn't the knight use a nail as a sword? That would make him short. And the radiance is roughly seven knights tall. So, while bigger than the night, the radiance is still a bug. Cyn erased all life from two planets, and fully assimilated one. While I don't play hollow knight (nothing against the game, I still want to try it) from what I understand, the radiance is a bug-sized sun god thing. Cyn is throwing around black holes like f**king gojo. And she can use holograms.