What Weapon would a Chemist use?

[BlitzAceRush]

We have an alchemist. It makes potions. We don’t need a chemist to make ... potions...

Chemist doesn't need to make them, it uses them in battle, an army field medic isn't out there in the middle of battle weaving bandages and brewing antiseptics just like a hospital doctor isn't going to be practising in the middle of a battlefield, you can have the same skills applied differently or used by two separate groups to achieve different goals.
Alchemist create and use potions in a controlled environment, Chemist takes them into battle to use in combat.
No different than a Blacksmith creating a sword but not being a seasoned warrior where as the Gladiator is but has no idea how to forge one.