Weapons that are "holstered" in the back can be damaged and shot off by critical hit as well as active ones. Any weapon in the back cannot fire, as these weapon(s) is/are inactive.
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, 4x Orkan 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.
Another way to use this is when one of your weapons on either robot above has been blown off. For example, if you are a Butch and you just lost a Trebuchet, you can always rely on this ability to get another set of 2 Trebuchets and continue your sniping act. This way, you don't have to worry so much about reduced firepower because you lost a weapon that can do high damage.
Just like Dash, even this ability can have weaknesses when not used properly or when using weapons that reload much faster than the ability cooldown. A Jesse using Magnums or the Butch that is using the Zeus is not good for the robot, as both weapons have reload times faster than the ability cooldown. The purpose of this ability is to exploit reload times, allowing sniper weapons to fire much faster. This is even worse with the Butch as you have only 50% of your firepower active and is bad for the Zeus as it has only 5 seconds of reload time and has the potential to do only half of the damage compared to the number total.
Also, if a player accidentally presses the "Quick Draw" button and the reserve weapons are still reloading, this can be troublesome to the user as he needs to wait another 10, 15, or 20 seconds to draw back again. This can make these very expensive robots very useless because he misused this ability strategically, especially when you have a Butch with 4x Kang Dae which can't fire until fully loaded.
Effective uses of this ability can make these robots a nightmare to enemies.