How is the item supposed to work? Does it make the entire Dual Blades line applicable when wielding the weapon, or just the nodes it has specific bonuses for (Dual Blades and Belgothian’s Shears)?
I tested the weapon a bit, and Belgo procs like expected, but AQC and Whirling Death don’t seem to. This leads me to believe the latter interpretation is correct, but I am unsure if that is intended.
Afanasenkov, and your hunch, are both correct. The modifier for Belgothian Shears include overriding Shears’ dual-wield melee requirement so that you can use it for the repeater gun, just like Stormrend allows the player to use Primal Strike with a one-handed weapon.
To make the entire line applicable, you’d need to give modifiers to every skill in the line.