Turns out, the "swords," or bills, of billfish like marlin, sailfish, and swordfish, are indeed used for hunting, but not as devices to impale prey. Rather, they are wielded as scythes to swipe at larger prey or through schools of smaller fish, knocking them senseless so they can be easily gobbled up.

Do swordfish regrow its sword?

Fishermen often catch swordfish with mangled swords, so breaking one isn't fatal, but they do help their owners swim faster and feed. And they don't seem to grow back, at least not for adults.

Are swordfish born with swords?

At birth, the 'sword' is not present on the swordfish, but rather a set of teeth are. Over time the teeth are lost and the 'sword' grows as the fish matures. They are also born with scales, which disappear by the time full maturity is reached. Swordfish are considered fully mature at 4-5 years old.