The gun is said to be the great leveler. It doesn't matter how big or small you are, weak or strong, skilled or unskilled at fighting, a shotgun blast to the chest will take you down. Obviously, in a world of supernatural monsters, the humans are going to want a boatload of guns. Sometimes, though, you need something sharp to finish the job, and sometimes you have to fight with whatever you have on hand. And sometimes, you just REALLY have to blow something up. Nuke it from orbit; it's the only way to be sure.
ARMORY is a supplement for the core line of White Wolf's World of Darkness. It's critical for mortals to have some kind of arsenal, but mages need kevlar vests as much as anybody and a werewolf might find an antique silver butter knife to be the most effective weapon against her opponent. ARMORY has all that and more.
Also, it seems that every group has a gun nut, or a sword enthusiast, or someone who just plain knows how to brawl (I had an artilleryman, for example). They know a lot more than the ST about the equipment they specialize in and can overwhelm you with their technical knowledge. ARMORY at least keeps you informed about the difference between ACP, LR, and magnum ammo.
I originally thought ARMORY would just be a list of equipment and how it modifies dice rolls. And how much stuff could there possibly be to describe? Well, ARMORY covers improvised weapons, guns of all kinds, heavy weapons and explosives, WMD's (chemical/biological/nuclear), vehicles, and equipment. And it doesn't just list weapons, it tells how to use them. This is really invaluable, and you will learn a lot about how firearms work, how bullets deal damage, what kind of nerve agents are out there, and how a kevlar vest protects you when it is nothing but tightly woven cloth. It is really quite fascinating (and a bit chilling) to read and really understand the myriad ways that human beings have for killing each other.
ARMORY also includes new combat merits, including fighting styles. The "sniping" and "Spetsnaz knife fighting" styles are probably the most impressive.
Overall, ARMORY is an amazing book and so much more than an equipment list. After reading ARMORY, you'll have a much deeper understanding of weapons and defenses, and knowledge is a powerful weapon in the World of Darkness. But a Magnum Research Desert Eagle is even more powerful.