Weapon Attack Bonus (+1 at 23, +2 at 25, +3 at 30)
Weapon Damage Bonus (+1 at 23, +2 at 25, +3 at 30)
All the AC, Attack and Damage bonus stacks with equipment.
This means, that a level 25 fighter (+2 AB) using a Masterly Damask weapon (+3) would have a total bonus of +5 AB, and thus pierce most damage reduction effects.
From the NWN Wiki:
I can confirm that stoneskin is in fact still absorbing my damage when I use a masterly damask weapon. It appears that the DR penetration that I much coveted with this build is absent.Description: This spell grants the target creature damage reduction 10/+5. The spell absorbs 10 points of melee damage per caster level, to a maximum of 100, before collapsing.
I am available for testing at your convenience