Hi,
Archer Heavy for pdef/resist/hp/pvp slow for pvp.
Archer Light for evasion/atkspeed/ for farming.
Daggers should always stay light.
My l2 archer is Skittle, You'll find me l2eternity. I wear vesper heavy vs elegia sets. There's many reason to it but the main reason is i like Vesper Look more than elegia. And I'm the only one that wears vesper for end-game pvp. It' never failed me, welll maybe once or twice but not as much as light has. o.O