Sidearm Pistols
P2016
Section Unfinished
RE-45
Best secondary, but P2016 is perfectly viable too. Damage dropoff is really nasty, but it is a sidearm... though accuracy while ADSing is surprisingly good. While you might be tempted to ADS due to the excessive bullet spread, that makes it incredibly hard to track pilots; just leave it non-ADSed and let the bullet hose hose bullets.
Craftidore
B3-Wingman
This is unequivocably the worst weapon in the game. Unlike the Kraber, it's not just a weapon requiring high skill, it's actually genuinely bad. The B3 Wingman does a pitiful amount of damage (even headshots), has gosh-awful damage falloff, a slow fire rate, and ironsights that make it nigh-impossible to see what you're aiming at.
To kill someone with a B3 Wingman, you need every advantage you can get. It's not enough to notice the enemy first; you'll lose the firefight anyway. It's not enough to hit every shot, even land headshots; you'll lose the firefight anyway. To kill someone with a B3 Wingman, you need to outflank the enemy, hit every shot, have better positioning, dodge their fire, and probably use your tactical too. Every kill is either earned with blood, sweat, and tears, or was a stolen kill.
One might assume from this that you should never use the B3 Wingman. Quite the opposite in fact; it's a surprisingly fun gun to use, in a Darksouls kind of way. Furthermore, you'll find your movement, strategic thinking, and other combat-adjacent skills will improve quite a bit while using this gun, simply out of necessity.
Craftidore