1.
concerned with or affecting the spirit or soul
unearthly love
2.
suggesting the operation of supernatural influences
an unearthly light
he could hear the unearthly scream of some curlew piercing the din
The word "dexterity", to do with skill is related to the right hand. The opposite of the word "deter" is "sinister", to do with evil, it is related to the left hand.