Practise thyself even in the things which thou despairest of accomplishing. For even the left hand, which is ineffectual for all other things for want of practice, holds the bridle more vigorously than the right hand; for it has been practised in this.

-Marcus Aurelius

You can be a left hand, right eye dominant shooter. It's all about what you practice. Ned probably grew up getting his knuckles rapped for using the devil's hand and just knows those skills better now.