Per the Damage article on the gw2 wiki, the tooltip damage formula is:
Tooltip damage = (average weapon strength) * Power * (skill-specific coefficient) / (level-based Armor value)
Thus, basic algebra (assuming I still remembered how to do that right, it's been a little while haha) shows that the skill-specific coefficient algorithm is:
Skill-specific coefficient = (tooltip damage * level-based Armor value) / (average weapon strength * power)
At level 80, level-based Armor Value = 2600.
P.S. Math I did for finding the skill-specific coefficient, used my DD ele with steady weapons:
dmg = wep * pow * skill / armor
dmg * armor = wep * pow * skill
skill = (dmg * armor) / (wep * pow)
129 = 238 * 2004 * skill / 2600
129 * 2600 = 238 * 2004 * skill
skill = (129 * 2600) / (238 * 2004)
skill = 0.7032154179
dmg = 238 * 2004 * 0.7032154179 / 2600
dmg = 129
Edited by TimeBomb, 10 July 2013 - 11:53 AM.