A minor point: both displayed and actual weapon damage round down to the nearest point, so an average Kingslayer Feral Axe with +10 Minimum and +40 Maximum Damage has exactly 97-470 (283.5 average) and the Decaptitator has exactly 181-519 (350 average). Beyond this point, damage is rounded down to the nearest 1/256 point at each remaining stage of damage calculation.So I just checked about the Feral Axe and ... I'm not sure. With the same ias I could hit an 11 frame attack with it, instead of a 13 one. Faster is always better, so it's definitely appealing. But a quick calculation of the dps shows me that the Decapitator would still come out first when it comes to damage. Problem is, I'm not sure my calculations are accurate. As a matter of fact, they probably aren't.
Anyway, here they are, and maybe someone else can jump in and correct me if needed.
A slightly more serious point: there are 25 frames per second so you'd multiply that by 25/11 and 25/13 respectively, not 24/11 and 24/13, to calculate weapon DPS (so ~644.3 and ~673.1 average respectively).
The most serious point: unlike when calculating weapon damage, you don't add 100% to level 9 Vengeance's +118% fire, lightning and cold damage since weapon damage is 100% physical but 0% fire, lightning and cold damage, so you multiply by 1.18 (*3), not 2.18 (*3), resulting in ~2280.9 and ~2382.7 average elemental DPS respectively from Vengeance.
Sharp Grand Charms have +(7-10) Maximum Damage (and +(49-76) Attack Rating) each, so 4-6 would give you +40 or more in total, and a rare ring can have +(5-9) Minimum Damage, so that's fairly realistic... and then there are War Traveler Battle Boots, which add 15-25 Damage all by themselves.3) I don't know how realistic the +min and +max dam values of 10 and 40 are; if these are bigger, the difference in dps would become smaller