I know Jenassa will duel-wield in melee. What about the other followers? I didn't have much luck with Lydia but didn't test it that much either. Does the follower skill set have anything to do with it? I'm particularly curious if Aela the Huntress will duel-wield. Any feedback appreciated.

I think it′s basicly a pre set choice, if there "default" gear is a sword and shield, that′s what there gonna use, the only way I seen to make such followers more offensive is giving them a 2 hand weapon.

Yeah, I hope that's not the case. I did read a comment in a different forum about Lydia dual-wielding but I can't confirm it. Aela's melee default is sword and shield so I'm a little discouraged.

As long as they have the 2nd weapon significantly stronger it should make them dual wield thats what i think, cause i gave lydia a firebolt staff and she was sword/staff.

That's encouraging!