How weapons and auto attack work

[Cezar]

Hello everyone! Yesterday with guildys we was discussing about how attack work, some of what i understood is: (i have couple questions)

attack in primary hand is:
[(base dmg * 2) + PG damage bonus + weapon damage bonus ] / delay

where pg damage bonus is 1 point every 3 lvls past 28
weapon damage bonus you can see from ZAM

1) Is it correct till now?
2) Seeing on ZAM i see dmg bonus is 8 for jade mace (for example) so with a lvl 50 pg:

[(8x2)+ 8 + 8] / 18 = 32/18 = 1,77 ratio

But Swiftblade of Zek is 11/18 without bonus, so:

[(11X2) + 8] / 18 = 30/18 = 1,66 ratio

Is this possible? Well i seen Short sword of Ykesha have a dmg bonus of 21, so:

[(8X2) + 8 + 21] /24 = 45/24 = 1,87 ratio

Its definatly impossible, so i am missing something!

3) how it work for sec hand? Its just dmg? or maybe dmgx2?

4) (bonus question) whats better for offhand? slow or fast weapon? Any good and cheap one for a War?