Tim and Tina,
In line 8, I think "half in half" is simply that she has shared with him half
of her own "surrounding air", air (sheathing) that contains her magic, and now
surrounds exactly half of him.   She has lent her goodness to him, but being
less than the full dose it is a fragile wrap - delicate air which must,
therefore, be protected - "No, no! Go from me."
 
Best, Jay Anania