Weapons are distinguished by class (Flexible, Edged, Blunt, etc), and each class has a corresponding weapon skill. If you have the weapon skill, you may use the tactic associated with the weapon class. For this reason, the term "weapon" is used interchangeably with "weapon class" throughout these rules.
In the Character Creator, you are able to choose a type of weapon when you select a weapon from a class. For example, if I add a Heavy weapon to my inventory, the Creator will ask me to select a type of weapon (a tetsubo or greataxe, for example). Mechanically, there is no difference between types of weapons within a class—the choice is purely cosmetic. So if you're not using the Character Creator, you can ignore weapon types.
Some weapons, like Firearms, deliver lethal damage that is volatile, which means that instead of dealing a specific amount of damage, the weapon deals variable damage. Roll a d6 to determine how much damage is dealt with each successful attack. Volatile damage is not subject to critical success or failure.
Some weapons, like Heavy weapons, have the tactic Two-Handed, which means you can't wield a shield or another weapon while wielding this weapon. You do not add the defense bonus from your shield if you're carrying a two-handed weapon.