Scimitars and weapon finesse.

[MisterPAIN]

Enough said, I think they deserve to be affected by weapon finesse considering they are the same stats as rapiers.

Duel wielding mmm kay?

[Snoteye]

Can't be done.

Also, scimitar != rapier. There's a reason the rapier is the only medium sized weapon affected by the feat.

[9lives]

Rapiers don't count as light-weapons in the off-hand, I believe.