is two weapon fighting viable as a pally or would i just be better off attacking with the one handed weapon
im thinking going the power attack route if i don't shield bash
any advice its for society and don't want to screw up a society build
It is viable, but it's extremely feat hungry and doesn't really get good until you get to mid-high levels. I would absolutely suggest human for the bonus feat.
Power attack is always good.
Getting the TWF through two levels in ranger would be a good way to cut down the dex requirement.
If you're going to take a 2-level dip, go into Brawler instead. You get 4/day martial flexibility, a bonus feat, and can Flurry with a monk weapon (such as 9-ring broadsword) or close group weapon (such as your shield bash). That way you only have to enchant one weapon.
It's a tough call between Human for the extra feat or Dual Talent Human for the double ability bonus to make the dexterity requirement much, much easier.
Double Slice is useful but not necessary, and it's far, far less important than picking up Dual Enhancement to give both your weapon and your shield the Divine Bond bonus. Free double Divine Bond is also a significant reason not to dilute Paladin levels.
One interesting option would be to replace Improved Shield Bash and the full-on TWF chain with Improved Unarmed Strike, Dragon Style and only basic Two-Weapon. You can cap your dexterity at 15 and use TWF to make a single Dragon Style 1.5xSTR unarmed strike (anything from a 'punch' with your shield-hand to a plate-boot in the gut, unarmed doesn't specify). An Amulet of Mighty Fists is completely unnecessary since you're already putting enhancement on your unarmed with Dual Enhancement and the Body Wrap of Mighty Strikes is a cheaper way to enhance unarmed. Within the levels of PFS, you'll probably get a lot more out of one powerful offhand than two weak ones, particularly when your point buy isn't spread thin.
You can also use this setup without a shield to seamlessly switch between two-handing a weapon for all single attacks and going TWF for full attacks.