The Graal is one of a long line of krogan weapons used to hunt thresher maws. Its ammunition consists of oversized flechettes meant to pierce thresher hide and create deep wound channels leading to massive blood loss. For additional firepower, the weapon is double-barreled, and, as a last resort, possesses blades to cause internal injuries if the wielder is swallowed by the thresher. Using a Graal on a humanoid target has predictably grisly effects. Its shots can be charged for more damage.
The Graal can be charged for up to double damage, but this is risky to do from sticky cover on higher difficulties. A safer way to use charged shots is from standing cover behind walls/pillars you can simply run behind and pop out from. The Graal only expends one shot, regardless if it was charged or not.
Because the Graal shoots slower, but heavier flechettes, there is a noticeable delay between shooting and the impact on your target. It makes shooting moving targets a bit tricky, but this can be remedied by leading your shots. It takes time to get used to this if you have been using the classic shotguns.
The Infiltrator'sTactical Cloak power registers a shot fired when you start charging the Graal, rather than when you actually fire a shot. That means if you are cloaked and start charging you will uncloak whether you've fired or not. Inversely, if you cloak after you start charging you can release your shot without breaking stealth.
Combined with two regular shots, this allows you to unload an entire clip before the cloak damage bonus wears off.
You may charge the Graal and still be able to sprint, roll, dodge, melee, or use most abilities without losing the charge.
The Graal Spike Thrower is a great weapon for Vanguards. A charged Graal will fire at the beginning of a Biotic Charge and if the fire button is held down the Graal can be fired a second time immediately after charging. Because of the Graal's high accuracy, this allows you to deal a large amount of damage in a short period of time.
In contrast with other conventional shotguns, the Graal ignores armor damage reduction, making it considerably more effective against armored opponents especially at higher difficulties.
The Graal is highly accurate, even without the Smart Choke mod. With it, it can be used even at long range.