Shields don't have to be a wall of energy. In fact, it doesn't make sense for shields to be a wall of energy if you think hard enough about it... when I first was reading into shields I thought this naively as well, but read the link below and be enlightened.
In fact, if you could manipulate energy and form it into a shield, why not use the same manipulation effect to deflect incoming energy rather than put up a wall of energy?
See
here.
Brian