Has anyone had luck getting Serana to use a bow (either normal or crossbow)? I was fed up with her trying to kill undead with ice magic, so I gave her a nice fiery crossbow and... she continued with the ice. Am I wasting my time with her? Should I just try a different range weapon? Thanks for any anecdotes you have!

Mage followers won't use bows for ranged attack.

Thanks! Then I'll go with staves in her case (and take a bit of friendly fire).

She will use a bow when she runs out of magicka. But that takes awhile. When fighting indoors, the fights are usually short and sharp so she won't use a bow. Outdoors, however, the fights tend to be longer, particularly against dragons. That's when she will resort to using the bow.

Added: Actually, I like watching Serana use the Dragonbone Bow I gave her. She looks rather neat staring up at a dragon and shooting at it. So by all means, give her a bow!

She's also quite good with one-handed weapons when she's in melee range. Her default one-handed weapon is an Elven Dagger. I gave her an ebony sword improved to Legendary and with a fire enchantment, and she's deadly with it when her magicka runs out and she's right in an enemy's face.

Wonder if she will do well with an crossbow? Found that Lydia was an killer with it, she had an bow but rarely used it however she killed a lot with the crossbow.
Might be that the base damage is so high she prefer it, don't like the basic ranged followers like Aela or the wood elf in Riverwood, they hang so far back they give little support and tend to not follow if you have to jump down somewhere.

Re that part, I didn't like how Faendal worked out either and was much happier when I switched to Jenassa. I thought they would be pretty similar but Jenassa was an improvement. (BTW Jenassa's also a killer with a crossbow but right now she's busy duping those pretty dragonbone arrows for me instead. I had Serana borrow Jenassa's crossbow.)

fairly certain mages don't use bows.... but if they have lighting... whats the point? More times than not, lighting kills bandits in one shot.

I like Jenassa as a follower, perhaps my favorite. But she tends to get a little wild with the crossbow. I don't know how many times she has hit me with it, dozens I am guessing! (I know she is hitting me because I gave her an enchanted crossbow and so when she hits me I catch on fire.)

Wow, I get hit a lot by followers with staves, but never with regular bow or crossbow as far as I noticed! I will have to test for that with something I would notice, maybe a paralyze bow...