Off-hand weapon dmg affix

I’m sure it’s been answered before but I couldn’t find it when I searched for it. In an off hand item like the mirror for rogues, does “+weapon dmg” increase only the off hand weapons dmg or both off-hand and mh dmg?

I believe DMG for oh is only for oh and mh only for mh. But if its ED it should work for both I think.

only for OH

This is correct.

WD and WD% is equipment specific.
ED and ED% is global on all gears