Bertelot
Bertelot, brother of Breuse Saunce Pite who loses his hand attacking the wounded Launcelot, attested in 1 source.
Bertelot appears in Le Morte d'Arthur as the brother of Breuse Saunce Pite, encountered in a forest ambush. The two brothers attack Sir Bliant together: "there met with him two knights adventurous, the one was Breuse Saunce Pite, and his brother, Sir Bertelot; and these two ran both at once upon Sir Bliant, and brake their spears upon his body" (Le Morte d'Arthur, Book XII, Chapter II). After Launcelot intervenes and defeats Breuse, Bertelot seizes a spear to attack the wounded Launcelot -- but Sir Bliant intercepts: "when Sir Bertelot saw there his brother have such a fall, he gat a spear in his hand, and would have run Sir Launcelot through: that saw Sir Bliant, and struck off the hand of Sir Bertelot" (Le Morte d'Arthur, Book XII, Chapter II).
Both citations come from a single chapter. Bertelot is characterised entirely through aggression -- first in the ambush of Bliant, then in his attempt to spear the already-wounded Launcelot. The loss of his hand at Bliant's intervention provides a symmetrical justice: the knight who attacked a helpless target is himself disarmed in the most literal sense. His pairing with the notorious Breuse Saunce Pite situates Bertelot among the Morte's predatory knights.
Appears in: Beings, Entities in Le Morte d'Arthur, British Tradition