Difference between Feel faint at something and Feel faint from something

feel faint at something—feel giddy or likely to lose consciousness at the thought or sight of smth.:

• Neptune felt faint at the sight of the slash wound.

feel faint from something—feel giddy or likely to lose consciousness because of fatigue, hunger, the heat, etc.:

• Feeling faint from the pain in her foot, Angie exited the alley.