I think the phrase "half of bravery is perspective" means that sometimes things that may seem daunting can be conquered by taking a new perspective on the situation.
Alternatively, it could also mean that people who display signs of bravery are actually not seeing things in full context - but rather a distorted perspective that makes them bolder than they perhaps should be.
Sound confusing? Here are some examples...
Example 1: A student is worried about their exams, because they are focused on all the terrible things that could happen if they fail.
By taking a new perspective, and focusing on all the positive things that could come with facing up to a daunting exam and acing it, this can instill bravery in the student.
Example 2: A motocross rider goes into every game completely fearless and unaware of the risks he's taking.
One day, a fellow rider has a serious accident in a competition, and this opens the rider's eyes to the true context of the situation - changing his perspective.
Next time he rides, he feels less confident and fearless, because he now realizes that he too could end up seriously injured.