Feather symbolism

In World War I and before, white feathers were given to British civilians and soldiers who were branded cowards. So when Miles lets the feather go in the end I think he's saying he's not going to let his fears of loss and James' disease control him anymore.

I believe it's also just a common symbolism of life and death(a beginning and an end). It's also been famously used in 'Forrest Gump,' as well.

Also a reminder of the angel wings and the birds representing freedom and rebirth.

I don't know if I'll make it, but watch how good I'll fake it