Attack power does increase weapon dps and, therefore, weapon damage. Every 7 str (14 ap) will increase your weapon dps by 1, so 14 ap would increase high-low weapon damage on a 3.3 spd 2her by 3.3 damage FOR WHITE ATTACKS.
In regards to % weapon damage moves, such as Mortal Strike, it would increase it by the AP coefficient for 2 handers. 0.236(AttackPower)*175%+67 at lvl 20 for Mortal Strike.
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The difference between Thorbias and Skeletal is 1 str and 2 stam. (Thorb-4stam10str, Skel-6 stam 9 str)
1 Strength will increase your AP coeffient by 0.472 (1 str = 2 ap; 2*0.236 = 0.472) This means for moves starting just over 200% that are normalized, you should average 1 damage more than you would from Skeletal on that particular ability.
Thorbias will increase your white damage by 0.143*WeaponSpeed over Skeletal Gauntlets. A weapon like BAR would see an increase by 0.143*3.8 = 0.542 Average Damage per Swing.
All this is without including the 25% damage increase from Seasoned Soldier. With the 25% included, MS should break the 1 Damage per Use mark at about 170% Weapon Damage; white damage goes up to 0.678 Damage increase per swing.
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Keep in mind, crits will double the difference between the two. So you would have to decide whether 20 hp or a slight increase in damage is more beneficial. Or just go by looks.