Item shows additional damage yet does less


I´m new here and registered to hopefully get some help with this issue I have.

So I found some new weapons which all have the green marker that shows they are doing more damage (+54) than the weapon equipped. Also the attack speed is higher and since I´m still a noob the currently equipped weapon doesn´t have any magical bonuses (it´s white). Going by the description of the weapons, the new weapon I found should be better in every regard.

Yet if I equip it, my damage goes down (Soldier: Cadence). Is that a known bug or am I missing something here?

Thanks for your replies.

Edit: I might want to add that I´m using a blademaster with two onehand weapons if that matters.

Maybe it’s overall weapon damage is less, and a shown DPS increase is only because of ASPD? Or maybe it has some conversion and + physical damage % on Cadence further nodes doesn’t apply as much. It could also have some flat DOT which is unaffected by Cadence, i.e. frostburn thus increasing DPS on autoattack tooltip, but not so much on Cadence.