Mellow harmony am i missing something?

[Deviant]

so i got this weapon and it have a buff wich says that it applies EXTRA dmg on my weapon from charisma

https://i.imgur.com/kq8i0T5.png

but when i activate the buff my weapon dmg is still same i for example got gloves wich apply my dexterity ability to off-hand weapon dmg and when i equip those gloves my weapon gets bigger dmg on tooltip so i was expecting for this buff to do the same but it doesnt what am i missing?

[Deviant]

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