Why is %IDotI better than % Damage on a 2H Weapon?

as Sebastian says is blood rune sword min dam 200 + rubies 99 damage= 299 min weapon damage, as you correctly supposed.
the flat damage is wrong, Sebastian make the right calculation, not 791 but 787 ( thanks for correction ).
the thing I don't understand is that 2.9 multiplier

299 baseWD
2.3 is wrong because the unique bonus of the sword is IDotI (i've check it now) so it is 3.3 the multiplier
(**) 2.9 I don't understand i suppose are ID on weapon; if it is so we have 50% behemoth+22% bonus set dragan + 18% unique values item dragan that make a multiplier of 1.9 not 2.9
so we have
(299*3.3*1.9+787.438)*2.2544=6001,59 with an error of 4.29%
with my formula
(299*3.3*1.18*1.72+787.438)*2.2544= 6289,87
instead of output value of 6271 with an error of 0.3% this time, with the correction of Sebastian.
the point (**) is what I don't understand, please Sebastian will you explain me?
sure that if the bonus of blood sword is IWD you made the goal...

p.s. sorry for the late answer, i take the child to the bed...

 

Remove all items, keep the weapon. Null all the talents.

Check if blood rune sword bonus is IDOTI, or, like I say, it is part of Behemoth (thus 2.9)

If that's IDOTI, you will get
(299*3.3 + 360) * 2.2544 = 3036

If that's Behemoth (and it is)
(299*2.3*2 + 360) * 2.2544 = 3912

 

ahahah...you anticipated me by a minute it's behemoth, you are right and my hypothesis is wrong (finally I reach the point)
i made the calc (299*3.3+360)*1.48 = 2568 and the stat window displayed 2566 output damage
is not more 2.2544 since I have only +48%ID as enchantement on the sword
with an error of 0,077% is obviously right (is almost the same number)
so the description of the unique bonus (in italian translation) is not right because it says damage on this item, but now I'm sure on how work dragan and bloodmoon

bonuses.
thanks to everybody, a lot of thanks, many many thanks for the discussion and for solving my doubt...​

 

Ah, thank you. I was looking at the gear.

Ahhh, and it does have incredibly low damage. I forgot about that item as another source of %WepDam. Thank you.

I'll update the main post to specifically mention the Bloodrune weapon as an oddball case.

As said:

Rounding errors strike again.

 

I have a doubt @_Baragain_, hopefully you can help me. I use longbow as my main weapon, but I wear Belicose Helmet, Gauntlets and Ring. So the bonus I get is only 22% weapon damage? Sorry if the answer is obvious but my calculations fail too

 

No problem. It should be as you say, but because of a long standing bug that shows no sign of being fixed, the helmet and gloves' 6% 2H lines will apply.
See the below from our resident longbow user and expert.

 

I will pass the Dragan set bug credits on to Wigger