I agree with all your comments, what i do is I usually start with the weapon as a focus point.
For my CAS, the additional weapons are a great source of inspiration (for a strong theme), so i end up with weapons and styles usually pretty dead-on with the CAS' persona.
The Fake Ashigaru used on Hilde allowed me to produce an asian version of Hilde, while the Trident weapon (see below) also inspired me into doing an Atlantis themed Hilde.
Of couse, there are obvisous choices the other way around : doing Joker or my Harley Quinn, i could not have thought of any other style than Dampierre's :
A few examples of weapon based CAS :
Caligula (Hilde Trident) :
Alien Space Marine (Futuristic looking sword) :
The Wasp with Voldo style and "insect claw" lookalike weapon :
When creating alternates, i also choose a weapon that would be suitable for the CAS' persona, provided the moveset is not way-off :
Caligula (Xiba Trident / cartoon style pic) :
The Wasp with "wasp sping" lookalike weapon :
Wasp this useful ?