I play a sword and board paladin that uses two-weapon fighting in Pathfinder Society.He has an AMAZING AC,great damage(especially against evil),and criticals quite a bit.If you are allowed traits and you use this build,take this Sarenrae trait in the APG that gives 2 extra damage on criticals(I don't have the book on hand..).
If you are just going to use two weapons,use either tri-bladed katars or the wakizashi.You can be a half-elf and take the alternate racial trait to get EWP with either one.
Your stats for a 20 point buy should be Strength 17,Dexterity 15,Constitution 14,Intelligence 7,Wisdom 8,Charisma 15.They're petty MAD.Increase Strength at 4th,Charisma at 8th,and continue in that pattern.Buy an Ioun Stone or stat belt to get your Dex up to the levels required for ITWF and GTWF.Good dips are either fighter or samurai.Samurai you should take at 1st level if you want to use wakizashis.
Feats should look like this:
L7:Improved Two-Weapon Fighting