The Valiant is a sniper rifle tested by Alliance soldiers during a series of harsh survival exercises on the planet Kruljaven. This streamlined weapon employs a sophisticated fire-control system that improves accuracy by stabilizing the barrel during targeting. Although this comes at the cost of reduced capacity and rate of fire, most soldiers find the increase in precision and quick reloading time a worthy tradeoff.
The Valiant fits in between the M-92 Mantis and M-97 Viper sniper rifles, doing more damage than the latter, with less than the former but holding more spare ammo, while still providing a higher rate of fire than either. The Valiant weighs the same as the Mantis when both are fully upgraded, has the obvious advantage of multiple shots per reload, and still has the ability to snipe targets in one shot on gold, much like the Mantis.
The Valiant does more damage and fires faster than the Viper, thus functionally rendering the Viper obsolete even though the Valiant has a 50% smaller clip. That said, the Viper is much more accessible due to its uncommon rank, while the Valiant is ranked as ultra-rare.
The Piercing Mod is very effective on this weapon, especially when fully upgraded as the damage lost isn't significant enough to be of any real hindrance. Two or three well placed shots can quickly end multiple targets if used correctly. While weapons like the two Widows can do this with single shots due to their higher damage, both are very heavy, have a much slower rate of fire, and a slower reload.
Reloading the Valiant is extremely quick, when reload cancelled, it can be nearly instantaneous. If this is used, it also gives an extra benefit of giving the Valiant a near-constant rate of fire, but this also means you will burn your ammunition supply very quickly. But done correctly, the damage per second can very easily become unmatched in the sniper rifle category.
The Valiant works better against shielded enemies such as Geth Hunters and Centurions than any single shot sniper rifle, as it can bypass the shield gate (the mechanism which prevents excess damage from affecting the target's health/armor after going through the shields). In one magazine and without equipment, for example, the Valiant can kill a Geth Rocket Trooper on Gold difficulty whereas a Widow would leave the target with a modest amount of health.
With the addition of the Sniper Rifle Amp gear, it is possible to further increase the damage of the Valiant by up to 15%. This increase can drop almost any shielded infantry in just two shots, one shot for shields (or two with tougher enemies), and one for the health. The overall damage of the Valiant becomes so devastating that the weapon becomes unmatched for quickly eliminating groups of infantry on any difficulty.
Alternatively, if playing as the Salarian Infiltrator, it can be useful to have the Operative Package Gear, as this increases both the damage of the Valiant and that of Energy Drain by up to 12%, which makes it very easy to fight geth on any difficulty.
The Vulnerability VI gear is also very effective with the Valiant. While the Valiant is capable of headshotting enemies on Bronze or Silver, only specific classes can consistently kill with one headshot on unshielded enemies. This gear would allow this problem to be lifted either partially or completely, depending on the level of the gear. It also makes the Piercing mod an even better option since it can boost the damage to the point where it would not effect the one shot kill ability of this already powerful weapon.
In comparison with the Black Widow at the same level, the Valiant does around 40% less damage per shot. However, the Valiant is a lot lighter, fires faster, reloads faster, and has drastically less recoil. This results in an actually superior damage output per second and less exposure to risk since the shots come out more rapidly. This renders the Black Widow more or less pointless if you have the Valiant as you'll do better damage in shorter intervals, though the Black Widow's innate piercing is a significant advantage.
In comparison with the M-98 Widow, the Valiant does about 40% of its damage per shot, and its full clip will come out more than a single Widow shot as a result, this also means the Widow stores more damage total between trips to an ammo box. This assumes the Valiant is level 1-2 and the Widow is perhaps 4-5 or higher (a common situation due to the latter being merely rare quality). Once a target's shield is removed the Widow will fairly easily out damage the Valiant (with reload cancelling) and provides longer endurance. This makes the Widow probably better for classes with a powerful shield strip such as the Salarian Infiltrator. Classes without this though are likely better served by the Valiant being able to apply part of its damage through the shield due to its semi-automatic firing mode.
Despite its high damage, the effectiveness of the Valiant is drastically reduced when playing on Platinum. The enemies health and/or shield levels makes said weapon incapable of performing one shot kills on anything other than Husks, unless using Tactical Cloak or Adrenaline Rush. At that point, it can adequately kill basic level troopers, and soften up harder enemies.