Board Thread:Dark Souls/@comment-6003396-20130307003836/@comment-667748-20130614213540

If you search around the forums (on the internet, not here), you can find a few good threads and formulas. Be warned though, it is complicated.

If there are a rules of thumbs to follow though:
 * 1) AR=>Damage is exponential. This means that a 400AR weapon will do more than twice the damage of a 200AR weapon (not even taking into account armor). When reaching very high numbers, little changes can make a big difference.
 * 2) AR is only relative to the moveset: a multiplier is associated to each move of a weapon. For example, the Black Knight Greataxe has very high AR, but its damage output is quite poor. When comparing AR, make sure the weapons have comparable movesets.
 * 3) As a rule of thumb, players/monsters low armor vs Strike/Thrust, normal vs standard, and high vs slash. For equal damage weapons, thrust/strike should be preferred, whereas slash avoided. The difference is usually quite substantial.

That's a quickly compiled result of the info I've found.