I'm creating a set with a Divine Veil, Skolver Coat, Grey Owlite Shield, Divine Avenger, Final Flourish, Gran Faust, and ???
The ??? has to be a handgun.
These are the choices I have for handguns.
Blitz Needle
Argent Peacemaker or Sentenza
Polaris
Nova Driver and other Alchemers
Valiance
Callahan
I'm having trouble deciding, so which one of those handguns would go good with the set I'm using?
Blitz Needle is best used against Vanaduke. It is rarely a good choice otherwise. Not good for a general-purpose loadout.
Argent Peacemaker is good for a swordsman's sidearm, but not much else.
Sentenza is great for Lockdown, and not much else.
Polaris is fabulous against turrets, Vanaduke, most other bosses, and even against enemies it's not supposed to fight. Get it.
Alchemers are pretty strong, but are best used by a gunslinger, which your armor isn't built for.
Valiance is a great utility sidearm. Pushes back anything you don't want in your face, and keeps your foes at range.
Callahan is a gunslinger-only weapon. Don't get it.
Choose between Polaris and Valiance. Both are great utility sidearms. Both are great in Lockdown. Polaris is great against most enemies, while Valiance is good against all enemies.
It's a toss-up between the two. I'd say Polaris.