I know there isn't one in core, but since they put out feats every now and then in their other products (few of which I have), I was wondering if there is a feat that allows for fighting with a one-handed weapon in each hand and only suffering a -2 penalty for Two-Weapon Fighting.
Thanks in advance.
I haven't seen one, but I guess it all boils down to what your DM will allow. I use that feat a lot, and since PF is supposed to be at least somewhat backwards compatible with 3.5, it's really up to your DM. You are essentially spending a feat to increase the damage dice of your off-hand by one step, which isn't a whole lot different than just taking an exotic weapon, so I personally don't see a problem.
Maybe someone else has seen an official ruling, but my opinion is that it should be ok.
I think the provenance of "florentine" dueling is pretty much a SCA invention. While it's certainly possible to dual-wield rapiers I don't see any problem assuming that they get hit with the brutal -4/-4 penalty.
That being said the introduction of a oversized two-weapon fighting feat with stiff prerequisites is probably not too game-breaking because by the time you unlock the feat the difference in DPR between a rapier and dagger fighter and a two rapier fighter isn't ginormous. The main advantage that I see is that it allows fighters to invest once in weapon specialization for rapier rather than have to get 2 sets of weapon specialization.