The Grey Wither Skeleton

Ok hear me out this is my idea of a more powerful more loyal Wither Skeleton.

The normal Wither Skeleton is a hostile mob you find in the Nether. To summon the Wither you need 3 Wither Skeleton heads and it drops a nether star to make a beacon. What if you could use the nether star for more than just a beacon you can use it to make a Grey Wither Skeleton pet.

How to Craft Grey Wither Skeleton Skull
Wither skull bottom middle row
Nether star middle middle row
Jack o'lantern top middle row
Stick bottom left row
Stick bottom right row
Iron Block middle left row
Iron Block middle right row
Iron Block top left row
Iron Block top right row
This will craft the Grey Wither Skeleton Skull.

How to Spawn*
Place it on top of two soul sand blocks at dusk (when the sun is setting)

How it Acts*
Like a tamed wolf a constant body guard. You can tell it to stay or follow.

How it looks*
It should look like a Wither Skeleton but grey. It should wield 2 iron swords.
It should have small spikes going down its spine.

Stats*
100 hp
12 damage
2x sprinting speed
Can add a chestplate to it
It can throw a sword but when this happens until it picks up its sword its damage is cut in half

Healing*
It should have a little blue bar above the players hearts to tell what its health is at.
Heal it with
Coal 6 hp
Bones 6 hp
Bonemeal 2 hp
Wither skull fill hp full
Its an undead creature so itstant damage and poison heal it.

I will edit this it is a rough draft of it plaz give me suggestions.