As a Spiral Knight, your primary weapon is in fact, the sword. You start with it pulled out, and it's something that does the most respectable damage in your arsenal.
FAQ.
Q1: Why Swords?
A2: Every civilization in history has used at least one kind of sword. You have the Greeks, the Romans, Middle Eastern Civilizations, Asian Civilizations, and of course, the Knights of the Middle Ages. Though sadly today Swords no longer have that big of a part in warfare, it's still used for ceremonial purposes and certain sports such as Kendo and Fencing.