Sidearms don't really have a role atm. They're just an extra thing to slap on.

Sidearms are made for one of two purposes:

1.) To cover a weakness in the main weapon.
2.) To quickly drop a target when you are caught while reloading.

Covering weakness is the main appeal of the SMG and MSec. Both are High ROF weapons with decent range. They are made to support the longer range main weapons as viable CQC weapons.

Dropping a target quickly SEEMS to be the main appeal of the Scram Pistol and Ion Pistol, with High Damage applications. The Scram gets a huge headshot bonus and enough rounds in a clip to down most targets in a single clip (Especially with headshots). Ion pistol is SUPPOSED to function like this, except the full charge doesn't do near enough damage.

Flaylock falls into the dropping a target quickly category. However, it's direct damage means that it's made to finish off weakened targets, not being able to hold it's own as a main. If you are caught with your pants down and all you have is the flaylock, you are going to be in a fight for your LIFE. The other weapons give you a fighting chance.

Knives are specialty weapons. Personally, I think the Knives, PLC, and Swarms should all be equipment, but that's just me.

Anyways: How to fix the sidearms IMO.

Scram: Nothing. It's fine.
SMG: Fine again.
MSec: Fine. These three are the sidearm trifecta.

Ion: Just make it fully auto. A High Damage, ROF monster with very limited range and lengthy reload. Give it an overheat too. If you fire the full clip, it overheats. Balances it because while you can be guaranteed a kill, you will have to wait for it to cool down AND reload. Last Resort weapon.

Flaylock: Needs universal splash radius across the tiers. Splash damage is fine. Direct damage needs a buff. Direct should be 250, 300, 350 as you advance. This allows you to kill in a single clip if you land 1-2 body shots. Splash allows for finishing off targets. Harder to use due to small clip and how it handles, it should also have the benefit of being versatile for the good user.

Knives: This patch was good. Knives are great where they are.

Just my 0.02 ISK on the matter. Take it as you will.