Attack value-Magical attack value

Hey guys i am wondering what the attack value and the magical attack value are used for?some of my friends told me that the attack value is for the dmg you are making with the sword and that it is really usefull for warriors with heroic strike and sura with enchanted blade because it increases the dmg with those two skills and because both of them get stronger with the swords dmg they increase and the other skills like whirlwind or dragon swirl!the magical attack value is the dmg you are making with your skills?  something else also i am wondering is the average dmg and the skills dmg for what are really for?the average for higher dmg with the sword an the skill dmg for the skills?  for a weaponary sura what is it more useful?average dmg to increase the enchanted blade or skill average for skills?i mean the average dmg is really increasing and the other skills but not the blade?  i would like an opinion from an experienced person in the game!ty!