Symbolism, Imagery, Allegory
The Arm Is Mightier Than The Sword
Us Lit nerds freak out about Beowulf for a zillion reasons, but one of those reasons is the fact that swords in Beowulf aren't—we repeat, aren't—a phallic symbol of total manly force. These swords are actually kind of... useless.
There are several different famous swords in Beowulf—so many, in fact, that you might have trouble keeping them straight.
First, there's the sword that Hrothgar gives Beowulf after he kills Grendel (1022).
Second, there's Hrunting, the sword that Unferth lends to Beowulf to fight Grendel's mother (1458). Unfortunately, Hrunting fails to do any damage to the monster, so Beowulf grabs another sword from her horde of treasure (1557).
This third sword decapitates her, but the blade melts when it touches her poisonous blood. After he brings the hilt back to the surface, Hrothgar discovers it is covered in engravings of the great flood and destruction of the giants:
Hrothgar spoke; he examined the hilt,
the relic of old times. It was engraved all over
and showed how war first came into the world
and the flood destroyed the tribe of giants.
They suffered a terrible severance from the Lord;
the Almighty made the waters rise,
drowned them in the deluge for retribution. (1687-1693)
Fourth, there's a gem-studded sword that King Hygelac gives Beowulf to celebrate his great deeds (2193). We can probably assume that this is the sword called Naegling, which breaks when Beowulf tries to use it to kill the dragon (2680).
There are a few other swords in the story here and there, but these four are the most important ones—to recap: Hrothgar's gift, Hrunting, the sword with the engraved hilt, and Naegling.
That leaves us with two questions: why are there so many different swords in the epic, and why do they so often fail to harm the enemy? (And nope, we really don't think the answer is just that swords are phallic symbols.) Well, there are many different swords in the epic for a pretty obvious reason—in a warrior culture, weapons are going to be pretty important, and there are a lot of them around. There are also different weapons for different purposes, and sometimes one sword can succeed where another fails, depending its quality and its history. Makes sense, right?
But the really strange thing in Beowulf is that, frequently, swords don't do their job. Hrunting won't cut Grendel's mother; Naegling snaps when Beowulf swings it at the dragon; the sword with the engraved hilt melts in Grendel's mother's blood. We're getting an inkling that the poet wants to remind us of the futility of battle.
It also seems that Beowulf does better when he uses his own body strength against the monsters around him, instead of weapons, which are almost like cheating because they give him an artificial advantage:
"I have heard moreover that the monster scorns in his reckless way to use weapons; therefore, to heighten Hygelac's fame and gladden his heart, I hereby renounce sword and the shelter of the broad shield, the heavy war-board: hand-to-hand is how it will be, a life-and-death fight with the fiend." (433-440)
Alternatively, at one point, the narrator suggests that Beowulf is so strong that his mighty strokes break blades in half, so perhaps Beowulf's heroism is greater than mere weapons could make it.