The classic text Beowulf uses several kennings (or compound two-word metaphors) to describe characters and actions in the story. "Hand-spurs" refers to the claws on Grendel's hand. The word spur comes from the Anglo-Saxon word spura, which means "to kick". This kenning is used to describe Grendel's powerful claws, and draws comparison to hardened steel. In essence, the kenning is giving Grendel's claws the qualities of a weapon, heightening his terrifying presence.
The second kenning, "heather-stepper" refers to a deer—specifically a male deer, which are called stags. Heather is a type of plant, and deer are known to walk among plants that it likes. In the context of the text, it is used in the description of Grendel and his mother's home, a place that is so desolate that not even a deer being chased by a predator would dare wander into it.