Halflings are small, and therefore 'small' sized weapons can be used with Power Attack. Just like how humans that are medium, can use 'medium' sized weapons with Power Attack. What makes NWN2 a little bit glitchy, is the fact that the list of Weapon Finesse weapons is hard coded, and therefore you can have a dexterity based power-attacking halfling or gnome.
PhantomLamb wrote:Here's the proposed build. There is a little bit of feat flexibility, and I'm considering One Weapon in the build (but not available in builder).
http://nwn2db.com/build/?285388
I would actually take Expose Weakness prior to Combat Insight. I just feel that the AC debuff from Expose Weakness will be more beneficial to your character. Improved Power Attack already gives you that +20 damage. I would also consider switching your Epic Deflection to Great Dexterity, as that allows you to make use of +'Stealth' items better. Many great epic stealth items have that +3 dexterity. For example some boots traded for 3,000,000 gold pieces had: +4 Dodge, +3 Move Silently & Hide, + 3 Dexterity.
I would also push the three last Duelist levels to be taken last.