My Lydia handled the few falmer she saw fine. My second follower was killed in a falmer fight, but there's some suspicion that it was friendly fire...an investigation is pending (*shifts nervously*).
Faendal, for me, had such a time with ice wolves. Not really with regular wolves or some other things, but for some reason, I always found him with an ice wolf on top of him, its paws on his shoulders, him collapsing to his knees...drove me nuts. "Oh heck, it's ice wolves...let's go the other way, you big wuss."