Shadowfax! A riley

Question

To begin, write something with how you write it,

In the middle, it’s what your tongue may be, make sure not to bite it,

At the end, he’s high above: Upper and Lower send their love,

Completely, I’m Shadowfax!

Answer 1

I think the answer is

Penumbra

To begin, write something with how you write it,

Pen

In the middle, it’s what your tongue may be, make sure not to bite it,

Numb

At the end, he’s high above: Upper and Lower send their love,

Ra (Upper and Lower refers to Upper and Lower Egypt).

Completely, I’m Shadowfax!