I vaguely remember a tale of one of King Arthur's knights fighting an opponent who is magically strengthened by being in contact with the ground. I think the protagonist defeats him by bodily lifting him off the ground until he becomes weak.
Does anyone know who the knight and his opponent were? Also, is this a medieval part of the Arthurian legends or a more recent invention?
Sounds like Maleger; from Brewer's dictionary:
Captain of the rabble rout which attack the castle of Temperance. He was “thin as a rake,” and cold as a serpent. Prince Arthur attacks him and flings him to the ground, but Maleger springs up with renewed vigour. Arthur now stabs him through and through, but it is like stabbing a shadow; he then takes him in his arms and squeezes him as in a vice, but it is like squeezing a piece of sponge; he then remembers that every time the carl touches the earth his strength is renewed, so he squeezes all his breath out, and tosses the body into a lake.
Maleger appears in Book II of The Faerie Queene, an epic poem by Edmund Spenser first published in 1596. If you have an eye for the language, you can find the text online; Maleger appears in Canto XI.
It may not be what you're looking for and I know it's not an original story, but in Terry's Brooks' "Magical Kingdom of Landover", specifically "Witches Brew" I believe, the defender of the throne wears a authorian style knights suit and has to battle such a creature. It's like you say in that it draws it's power from the ground and has to be separated from the ground to weaken and defeat it.
It's possible that this is what you read. It's an older series and you could have read it and forgotten about it.
