Important here is think on why choosing shortsword as an offhand weapon?Rapier is considering small weapon for a human when dualwielding it so there is the same -2 AB penalty if you wield rapier in your offhand too. I can see The RP reason but in weigth there isn't any different in rapier and shortsword.. rapier probably lighter actually. Due to your weapon of choice(3xcrit and 13-20 crit range) and weapon focus feats in rapier your offhand will suffer if going for shortsword instead of rapier I'm not 100% on this though so would be nice if someone could confirm this *nods*
Take four levels of bard. Chicks dig it.