How does this work? If I have bonus skill in a weapon as the Crusader (say, 2 @s), does that weapon get bonus to hit, to crit, does +2 worth of damage?

This might have been changed recently, but I think the damage bonuses for each level of weapon focus are: +1, +1, +2

Or looking at the overall bonus to damage, @ is +1, @@ is +2, and @@@ is +4.

Personally I think this skill needs an upgrade. It is useful at first but ultimately not that great. I think they should either increase the bonus and make higher levels of mastery much harder to attain (can you really master a sword by swinging it 20 times or whatever?), or leave the first 3 levels as is, but add 2 higher levels that would take playing through several maps to achieve. It would be much more useful if a mastered weapon had like double damage or so. Currently the advantage of weapon focus seems to pale in comparison to the importance of enchant scrolls and simply upgrading to better weapons, especially by the later levels.