Weapons that are "holstered" in the back can be damaged and shot off by critical hit as well as active ones.
The ability to switch weapons is limited by a cooldown timer that begins from the moment the switching process is started, the cooldowns are as follows:
How to efficiently use Quick Draw
The Quick Draw can be used to combine different weapons types and ranges or 4 of the same type of weapon for huge firepower. For example, 4 Orkans can deal a large amount of damage in two quick volleys as they can fire two and then switch out to the other two and fire again. This also enables the user to add some diversity to their setups as you can run splash and energy weapons on the same bot making you less vulnerable the weaknesses of a specific weapon type. This can be seen by considering that a Taran is ineffective against physically shielded bots, but the user can counter this by equipping 2 Orkans in the other 2 slots, enabling the user to protect themselves from physically shielded bots and energy shielded bots.
When running 4 of the same type of weapon, the Quick Draw is used to exploit the weapons reload time and is best used for weapons with quite a long reload time, such as the Orkan or the Tulumbas. When running with weapons that have a short reload time, by the time you switch to your sub weapons, your main weapons will have already reloaded or will be close to finishing reloading. This would effectively negate any advantage of having four weapons in the first place.