My main hand has +3 Luck, my offhand sword has +2 luck and my necklace has +1 luck, but my attributes show only 4 luck?

Seems to work as intended, considering it says When in Main Hand

That's dumb..... so is there a way to get it to say when in offhand or when held? Even the Daggers say it. Cause If not an entire build based on dual wielding is just out of luck the stats of a slots because shields and focus items for fasters give you benefits but rogues and dual fighters are left with nothing

attribute modifiers on items are related to an equipment slot
(unless they are added without one then it'd just say When worn or sth. like that)

you'll need to ask the better combat dev to apply hand modifiers for both offhand and mainhand (for dual wielding)
or ask the modpack author to handle this themselves

Will bring this to the proper attentions.