Shar-Teel build-up and NPC proficiencies.

I just got Shar-Teel on my evil party and soon after she hit level 3. Time to decide if i want to dual her now or wait until level 6-7.

I've read about the different options, but I want to be sure. Which scenario gives me the x4 multiplier and grandmastery in daggers? (already ++)

My group will be: PC (F/M multi), Dorn, Shar-Teel, Imoen, Viconia, Edwin.
Which melee/ranged weapons should I specialize my NPCs on?

My initial thoughts for melee were:

Dorn: two-handed
Viconia: Mace
Edwin: Staff
Imoen: Short-sword
Shar-Teel: Daggers
PC: dual-wielding scimitars