Welthow, Hrothgar's queen, is an astute woman whose influence in the kingdom is subtle, but unmistakeable. She plays an unusual role in this epic because women were typically abset or subservient in Angle Saxon culture and literature.
In this scene, Beowulf has just set the record straight on his swimming contest with Brecca. (Unferth tried to make Beowulf out to be a coward, but failed.) Beowulf's boldnes and spirit please Welthow, and she raises her cup to toast him and wish him joy in the feast. Welthow then pours mead for the men and considers pouring mead for Beowulf a "happy duty."
Welthow is pleased with everything Beowulf says, and she becomes his greatest ally in front of the king.