[@LukasVolkov]: Okay...

So to begin with Servants are almost always summoned in a very human state. In fact, in any normal case they have to be at least somewhat human(outliers in FGO are exceptions caused by weird circumstances). You can't summon a fairy. If you [i]could[/i], they'd need to be something along the lines of the Gorgon Sisters, where they were born from humanity in spite of technically being divine, therefore are "human gods" so to speak.

I honestly don't think Queen Mab is an inherently poor idea, but she'd end up being something more humanlike just by dint of a) being something manifested from human consciousness and b)being summoned as a Servant.

She could still have alien morals(I'm not opposed to someone who just loves to screw with people and doesn't get why it's wrong running around as long as they're not like, lolrandumbmurder or something) but she'd ultimately look more human and have a more human-like nature to her just by dint of actually being something that can be summoned.

If she [i]is[/i] created by humanity "metaphysical body" is completely unnecessary as the Gorgons don't have it.