For 10 points, give this nickname of Louis I of France.
Boleslav II of Bohemia was given this byname after establishing a bishop in Prague, and John III of Portugal, who established the Inquisition in that country, was also called this. Another ruler of this byname, who is less often called "the (*) fair," is mentioned in the title of the major work of Nithard, who wrote about that man's sons Charles the Bald, Louis the German, and Lothair going to war over Carolingian lands. For 10 points, give this nickname of Louis I of France.
Boleslav II of Bohemia was given this byname after establishing a bishop in Prague, and John III of Portugal, who established the Inquisition in that country, was also called this.
"the {pious}"