Bored, so here goes :
Damage type + power = increases the damage you do with all attacks of the particular "damage type", with a formula dependant on both the attacker's attack power and the defender's defense in that type of damage.
Example : You have 100 Piercing Power, your enemy has 60 piercing defense. You attack him with thrust and the damage you do will be the base damage thrust would've done at 0 to all stats for both, multiplied by 0.5% for each point of difference between your attack and his defense. So Damage*(1+0.005*(100-60)).
Damage type + defense = The defense against each type of damage as explained in the formula above, except if defense is higher than the attacker's attack, you get 0.5% reduction per point of difference between your defense and the attacker's attack.
Feral defense = The same as other defense types, except works specifically against animal attacks, and not sure if all of them (but it should be). It assumes 0 feral power on the animal's end.
Mining = Increases the speed with which you extract boulders from mine walls.
Culinary = Increases the speed with which you prepare food, except for making doughs.
Weaving = Increases the speed with which you turn cotton wool to cotton cloth.
Woodworking = Increases the speed with which you : chop trees down, chop woodblocks, plane boards, possibly craft wood related items(blurry memory but pretty sure that's how it works xD). It doesn't affect the speed with which you saw boards off a sawbuck however.
Digging = as you'd expect increases digging speed.
Common combat power/defense = Adds to every other existing "power/defense" stat, including feral defense.
Productivity = adds to every other existing civilian artifact stat, like weaving, woodworking, culinary, mining and digging.
I think that covers it, and I just rememebered someone had explained these the other day, so search a bit harder on the forums next time

It's likely out there.
Edit : Found the link too, so
viewtopic.php?f=5&t=10716 Feone's explanation.
Exactly 6.022 x 10^23 worth of Lach molecules.