Because she is older and has more experience and strength
While Grendel's mother is hard for Beowulf to defeat, he IS able to use a sword, where as he has to battle Grendel bare handed.
Under water, where Grendel's mother lived.
Beowulf and Grendel's mother fought in her underwater lair at the bottom of a dark, eerie mere (a kind of lake). The battle took place in the depths of the water, adding to the suspense and danger of the encounter.
Beowulf fights Grendel's mother, and kills her. He kills her with a sword that was made by giants, and he splits her into two.
Beowulf followed Grendel's mother's tracks to her underwater lair after she attacked Heorot. He dove into the lake and ultimately battled and killed her with the help of a magical sword he found in her lair.
While Grendel's mother is hard for Beowulf to defeat, he IS able to use a sword, where as he has to battle Grendel bare handed.
It is a matter of opinion regarding whether or not the behavior of Grendel's mother seems as wicked or unreasonable as Grendel's behavior. Grendel's mother was simply avenging the death of her son, so many would argue she wasn't as wicked.
Grendel's Claw (Arm) & Hroghgar's Closest Friend
In most versions of Beowulf, she has no name that is given; she is just called "Grendel's Mother".Some variations give her the name "Enchidna"
Fighting Grendel, Grendels mother and the dragon once he returns home to Geatland and is crowned king.
Grendels arm If its after the fight with Grendel's Mother then he took Grendel's head, the sword-hilt of the sword he used to slay Grendel's mother and cut off Grendel's head, and of course Hrunting the sword he originally brought to slay Grendel's Mother which was ineffective against her tough hide.
Her son's, Grendel, arm back that they took as a "victory" of killing him, and the sword that they used on him .