Item Id:72860 bug

Hello and sorry If I am not posting in russian but I really wish I Could.
My Topic is concerning the item 7280 which is a dagger called Mandible of the Old Ones that drops from Asira Dawnslayer in Hour of Twilight.
The dagger is acting like a 1.80 speed dagger although its speed is 1.40.
the Displayed off hand swing speed with it is 1.47 when it should be 1.15.This swing attack speed is smilar to a 1.80 dagger.
I considered The possiblity that my character stats display sheet is bugged but then I tried to count melee attacks with 3 daggers for 2 minutes without any considerable change in haste.The item 72860 behaved like a 1.80 dagger .
in 2 minutes I did 135 melee attacks with both and with the 1.40 dagger I did 162 melee attacks.
I hope this will be fixed and I thank you for your cooperation

i have the same problem