In addition to Prester [this name], a ruler with this name acquired the epithets "Softsword" and "Lackland," and he lost the First Baron's War after refusing to abide by a document he signed at Runnymede.
One ruler of this name from Bohemia was killed at the Battle of Crecy, while another ruler with this name advised his son Pedro to become emperor of one of his territories. In addition to that king from Portugal, one person with this as a surname was rumored to reside in (*) India or Ethiopia and be an eastern king friendly to Christian causes. In addition to Prester [this name], a ruler with this name acquired the epithets "Softsword" and "Lackland," and he lost the First Baron's War after refusing to abide by a document he signed at Runnymede. For 10 points, give this name of several kings, the most famous of which signed the Magna Carta.
One ruler of this name from Bohemia was killed at the Battle of Crecy, while another ruler with this name advised his son Pedro to become emperor of one of his territories.
{John} [do not accept specific names after "another ruler"]