Equipment can be used in your knight's equipment slots. Collecting new and better pieces of equipment and leveling them up is vital for being able to play more difficult levels on higher tiers. Equipment is unbound when first acquired. Weapons and gear will be bound to a single character when equipped; a bound piece of equipment cannot be traded, but it can be used in crafting to make an upgraded item. Bound equipment can be unbound at Vise's shop in the Bazaar.
Equipping a weapon to your knight will allow you to perform new attacks while exploring the Clockworks. There are several different classes of weapon, each with a wide range of types available that have their own specific strengths and weaknesses. You will arrive on Cradle in possession of a Proto Sword and Proto Gun, basic examples of the Sword and Gun classes of weapons.
The traditional weapon of a Spiral Knight, swords are powerful melee weapons that require you to get in close to attack enemies. As they are leveled up, they can acquire special abilities that require charging. Swords typically gain area attacks as charge abilities, but some swords are known to possess projectile charge attacks.
The standard ranged weapon in a Spiral Knight's arsenal, handguns are versatile weapons which can deal a variety of damage types to enemies. Though you need not worry about keeping track of how much ammunition you are using, every handgun will automatically take a moment to "reload" every few shots; make sure to adjust your combat tactics accordingly.
Bombs are a special type of area effect weapon that only have a charge attack, and thus must be charged up before each use. Once set, however, they explode in short order and deal significant damage to a large area. Bombs are an excellent choice for use alongside other knights using different classes of weapon.
Equipping gear bestows passive benefits to your effectiveness while adventuring, such as increased health in the Clockworks, greater resistance to damage or status effects, and other useful boons.
Armor provides a base level of protection to a variety of damage types, as well as resistance (or vulnerability!) to certain status effects. Certain armors can also provide added health at the start of each Clockworks expedition.
Helmets, like armor, provide protection from damage. While most armor sets come with a matching helmet, don't feel bad about mixing things up: it's entirely possible that having a little bit of protection to a bunch of different elements and damage types might just save your life!
Much like armor and helmets, shields provide protection from damage, and occasionally status effects. Having a shield equipped also allows you to block attacks, an extremely useful ability while exploring the Clockworks. Note that the statistics shields offer only apply if the shield is activated. If it is not, there is no advantage over not wearing a shield at all.
Trinkets can only be wielded by purchasing trinket slots with Energy. Once worn, they can provide a wide array of benefits such as increased health or resistance to certain damage types. Trinkets cannot physically be seen on a Knight.