The problem still exists with Monkey Grip in addition to Power Attack and Weapon Finesse.. so here is a non-Monkey Grip version with Kaedrins. (..no shield as a result, but other AC enhancements have been provided.)
Kneebiter | NWN2 Character Builder
Note that I did test it with variations - and this seemed the best all-round solution.
Ex. levels 19-20 could be Frenzied Berserker, to get Empower Power Attack. With just Power Attack it only adds 4 more damage per attack. Kaedrin's fixed Power Attack for a two-handed weapon to +6 damage (as opposed to the former +3 damage). If you add-in Improved Power attack then the FB's Empower Power Attack adds +8, though obviously with an additional -3 to attack.
In testing at these higher levels the AC was more important than the damage (..the inverse result at lower levels), especially considering *other* sources of damage.
Additionally, the Dualist class does provide an additional +1d6 (or average of 3) - that is somewhat close to Empower Power Attack's additional +4 with only Power Attack on - so the damage difference isn't that great.
The additional AC of +3 however, (assuming you have an Intelligence modifier), is substantial for this type of build. The additional skill points were nice as well.
As far as added damage though,
-it's piddly until you get Power Attack at character level 8.
+2 damage until character level 4.
+2 damage at character level 4.
+6 damage at character level 8 but at -3 attack (with Power Attack on).
+5 damage at character level 9 (via Elegant Strike).
So it's good by level 9.
The nice thing here is that you can add modifiers to both Strength and Dexterity to get damage that is NOT of the Critical/Sneak Attack immune variety. Of course Dexterity is being constantly improved so you have (beyond level 9):
+1 damage, attack, and AC at character level 16.
+1 damage, attack, and AC at character level 21.
+1 damage, attack, and AC at character level 24.
+1 damage, attack, and AC at character level 27.
+1 damage, attack, and AC at character level 29.
Note: all of this dexterity damage by-passes ALL damage reduction.
Additionally you have:
+2 damage and attacks at character level 17 via Melee Weapon Mastery.
+2 damage at character level 18 via Greater Weapon Specialization.
+1d6 damage at character level 21 via Precise Strike (..as mentioned above from the Dualist class).
+2 damage at character level 26 via Epic Weapon Specialization.
+1 damage and attacks and AC at character level 28 via Weapon Supremacy.
