The Deagle has the fourth highest damage per shot (without modifications or skill boosts) of all secondary weapons, after The Judge, The Locomotive 12G and Bronco .44. It has decent accuracy but suffers from a low magazine capacity, although weapon mods can compensate this, making it more accurate and deadly.
The Deagle takes approximately 1.8 seconds for a tactical reload, and 2.7 seconds for an empty chamber reload. This is somewhat slower than other pistols, with the notable exception of the Bronco .44.
The Deagle can be seen as a stronger, but less ammo efficient version of the Crosskill as they share similar attachments and are both plagued with smaller ammo reserves compared to other pistols. With only 30 rounds, it can have only three magazines (just under two magazines with the extended magazine attachment), making it extremely easy to run out entirely, so it is advised to be very selective of one's shots and always aim for the head.
The base accuracy (10) of the Deagle is marginal outside close range; at 15m or more properly aimed headshots may still miss. Various accessories that increase accuracy will solve this problem, though (except for the Marksman Sight) at the cost of some concealment.
The Size Doesn't Matter Suppressor and the Marksman Sight do not negatively affect Concealment, which results in the highest damage(35)/concealment(28) ratio for a silenced secondary.
The Deagle's highest possible damage per shot (65, or 80 with the aced Gunslinger skill), is attained by having the Ghost tree's Silent Killer skill aced (+30% damage for suppressed weapons) and modifying the Deagle with Asepsis Suppressor and Long Barrel. However, this makes the Deagle's already low stability even worse, reducing it to 3.
The Monolith Suppressor is a viable mod option for stealth, it offers the lowest damage reduction after the Asepsis Suppressor, does not affect Accuracy, and even boosts the Deagle's stability.
The Deagle is based on an "old model" Desert Eagle Mark XIX, chambered in the .50 Action Express caliber as evident by the safety switch, Mark XIX hammer style with tall serrations and "flush" barrel with visible scope rail mounts as current production models usually have picatinny top rails. The in-game magazine capacity of the Deagle is incorrectly large compared to its real-world iteration.
The in-game magazine size of the Deagle matches those commonly found on the .357 Magnum version of the Desert Eagle, though implausible as the in-game weapon uses the "flush" barrel made for .50AE rounds that won't fit and won't work with most smaller calibers.
The Deagle is further incorrectly portrayed as being weaker than the Bronco .44, Peacemaker .45 and Matever .357 as the .50 AE rounds it fires are heavier, larger and has higher kinetic energy overall compared to the rest. If depicted realistically, the Deagle would potentially be the most powerful of all pistols featured in the game.
In reality, silencing a standard Desert Eagle is implausible as the weapon's vanilla barrel does not have internal nor external threads to support a suppressor. This is even less believable with the Long Barrel attached as its smaller diameter means it is less likely to contain or support threading.
"Deagle" is a portmanteau of its full name originating from Counter-Strike.
The serial number of the weapon, located on the right side of the weapon above the grip just below the slide, appears to have been filed off, albeit crudely. This suggests that the weapon was illegally obtained as criminals normally remove the serial number off illegally-obtained weapons to prevent them from being traced back to their legitimate sources.
Shown in a video, the Deagle used to have the default pistol reload like the Crosskill's. This was used until a certain patch, which gave the Deagle it's own unique reload.