Final answer:
Beowulf's last argument against Unferth attacks his reputation and prowess as a warrior, demonstrating a discrepancy between action and words, a central theme in the epic.
Step-by-step explanation:
Beowulf's last argument against Unferth is a direct response to Unferth's earlier taunts and serves as a final dismissal of Unferth's capability as a warrior. Beowulf waits until the end to use this argument likely because he wants to establish his own reputation and capabilities first, before striking a decisive verbal blow against Unferth. This is an example of Beowulf's tactical approach to rhetoric and combat. Moreover, the timing of his rebuttal emphasizes his point by making it during a pivotal moment when strength and bravery are most needed, thus cementing his position as the superior warrior.
The argument centers on the notion of reputation and action over words, a consistent theme throughout the epic. Beowulf's contention might suggest that the appearance of the warriors, including their ferocious helmets and their reluctance to engage the dragon later in the tale, represents a troubling discrepancy between how they present themselves and their actual deeds. This contradiction could imply the decline of the warrior code and the culture that celebrates it, which is a significant point of commentary in the epic narrative of Beowulf.