How exactly damage is calculated?

[Morae]

So I got bored at trying to guess which items on AH are actually upgrades and how large at that. I wanted to see what stats I should be looking for and how much they are worth per point. All this kind of stuff.

So, I went looking how the damage is calculated and I did find enough information. The calculations are not complex at all, but there is stuff that I do not understand.

Problem is that when I tried adding stuff like dmg increases from abilities like magic weapon, it wouldn't give me correct results. An example, magic weapon gives 15% extra damage. I tried adding just that amount of increase, but it wouldn't just add up to what I see in game. Suddenly I noticed, if I put in 1.15^2, it gave me correct answer within 10dps window (when my dps total is around 40k). I tried using a random weapons I picked up and every time it was correct with that value. Where does that ^2 come? If I didn't use magic weapon it was giving me correct result. Does magic weapon suddenly decide that once its popped up 1h+offhand is dualwielding and gives bonus for that too on the same go? I don't even know dualwielding related bonus stats, but 15% to something seems to be left in my mind from somewhere...

Dunno what kind of accuracy I should be expecting, but somewhere at some point there seems to be now 1k dmg error and I can't find the culprit. Does anyone know the exact values for stuff and how to calculate things? That basic parts are very simple and give correct results, but add some buffs and other stuff and it suddenly gives strange results or somewhat high error margins.

If I'm just being stupid with something, please point out that too.

[Deleted]

Magic weapon is bugged in that it gives it's benefit twice for the damage value in the inventory screen. As far as I've read it doesn't actually give the benefit twice in actual gameplay though, so the listed damage is higher then it should be (but I've not tested this firsthand).

Just look for upgrades without taking Magic Weapon into account - it's a flat damage increase regardless of what weapon you use anyway.

[Morae]

Ooh that is good to know.