The M-5 Phalanx is the product of the Alliance's Offensive Handgun Project, a close-in weapon to be used with no loss of stopping power in comparison with a soldier's assault rifle. The Phalanx enjoys a ballistics advantage over most heavy pistols. Civilian variants are often purchased by colonists on planets that have particularly dangerous big-game animals.
The Phalanx does double the damage per round than the Predator, but it only has half the rate of fire; thus they have almost the same DPS.
The biggest advantage of the Phalanx is that while it doesn't have an overwhelming strength, it also has no overwhelming weakness.
The Phalanx isn't recommended on harder difficulties against tough enemies like the CerberusAtlas, since the Phalanx isn't as effective against shields and only moderately effective against armor, and the Atlas has large amounts of both.
Its higher damage and lower recoil compared to most SMGs can also make it a better secondary weapon for snipers.
When paired with the Pistol Piercing Mod, the Phalanx becomes very effective at taking down Guardians at close range on Bronze, with only 6 headshots required. This is very useful as it allows low level Vanguards who cannot use their powers to get past the shield to defeat them easily.
This can be a good sidearm for players who want to use their powers frequently due to its balanced nature and light weight.