The gunstaff is Jak's primary weapon in The Lost Frontier. Created by Keira Hagai prior to her arrival to the Brink with Jak and Daxter, the gunstaff was created with the ability to attach gun mods but also served as a melee weapon. Jak starts the game with the gunstaff, gifted to him prior to the first mission, "Find green eco fuel", and goes on to acquire firearm modifications over the course of the game. However, to start out with, the gunstaff merely serves as a melee weapon.
The mods obtained throughout the game are identical in name and function to those acquired during Jak II with the Morph Gun, with one exception. The Blaster, Scatter Gun, and Vulcan Fury reappear as the yellow eco, red eco, and blue eco weapons, respectively, though instead of the Peace Maker, a dark eco weapon, the gunstaff went on to attach the Lobber, a green eco weapon. Also unlike the Morph Gun, the gunstaff could not be put away, and upon acquiring a gun mod, could not select its normal, unmodified form.
Furthermore, Gunstaff upgrades could be found in brown treasure chests or earned in side missions. Each Gunstaff weapon has three damage upgrades, two rate of fire upgrades, one ammo capacity upgrade, and one upgrade unique to each weapon. Some upgrades can only be found in Hero Mode, requiring two playthroughs to collect them all.
The Blaster mod was created by the Aeropans and given to Jak as a means for completing the Danger Course, the challenge required of Jak to prove his ability to protect the eco seeker. Much like the Dark Warrior Program technology mimicking that of Haven City's, this mod mimicked the highly popular Morph Gun Blaster mod used frequently by the Freedom League in Jak 3, respectively (as well as by Jak himself during those games). However, whether or not this was done deliberately remains unconfirmed.
Once again, the Blaster fires a single, long-range blast of yellow eco, with a medium rate of fire and notable strength. It is generally best against enemies which you can pick off from a distance, like the armadillo, or used at strategic points against enemies like the Uber-Bot 888. It is also sufficient in detonating an eco amplifier from a longer distance. Furthermore, the weapon can function as a general mainstay, especially in combination with melee attacks to perform wastelander and aerial wastelander combos (see Blaster).
The Scatter Gun mod was found on Brink Island at the beginning of the mission "Look for a way off the island". Unlike the Morph Gun mod, the Gunstaff version was the second mod acquired as opposed to the first, usually coming before the Blaster. Similar to the Morph Gun, however, is its wide cone radius, shotgun-like function, shorter range, and high damage output.
It is best used against enemies who tend to fight up-close, like the tripodbot, silverback, or franken ape, and is particularly effective against clusters of close-range enemies, except when surrounded by them. However, it does suffer a lack of reload speed, and pales in comparison to the Blaster in time-sensitive or high octane battles. It can be used as a good mainstay weapon for the sake of preserving Blaster ammo, and thus should be used where possible, such as close-range eco amplifier operations or lone enemy battles.
The Vulcan Fury is a modified piece of Precursor technology discovered by a sky pirate. It was then patched into Jak's gunstaff, courtesy of Keira, just prior to the mission "Get supplies from Far Drop". It is identical in function to the Morph Gun Vulcan Fury mod, reminiscent of a minigun with a rapid rate of fire and diminishing medium-long range. It is noticeably effective against enemies prone to stunlocking, like the mutant ape and ghoul spider, though be watchful for ammo consumption. Although it has the highest ammo capacity of all gunstaff mods, it maintains a proportionate consumption rate.
In general the Vulcan Fury should be reserved for more pressing situations, and can be a game saver when surrounded by multiple enemies with limited health or immediate access to health packs, or in situations with tertiary threats to the primary enemy, such as the floating platform turrets operated by Aeropan commandos in Far Drop. It can also make quick work of high octane situations where more strategic encounters occur afterwards, for which the Blaster or Scatter Gun would be more appropriate.
The Lobber was discovered by Keira while at the abandoned research rig, and as such was available after the mission "Escape the laser lab" upon returning to Keira's workshop at the Phantom Blade. While the Lobber is technically unique to the gunstaff against the Morph Gun, it is effectively a green eco version of the Plasmite RPG, a red mod weapon from Jak 3. However, it is much shorter in range and lower in rate of fire than the RPG. It is nevertheless still useful in pressing situations, as it is very powerful and has a large effect radius. Similar to the Vulcan Fury, it should be reserved due to its high ammo consumption. Unlike the Vulcan Fury, however, it has a low ammo capacity to begin with but a low consumption rate per discharge.