What does Berahtoldus mean in Latin?

Berahtoldus, a proper noun, means “a male given name from a Central Franconian form of Berhthold”.

What is the genitive of Berahtoldus?

The genitive singular is Berahtoldī. Berahtoldus is masculine, second declension.

proper noun · masculinesecond declension

Berahtoldus m sg (genitive Berahtoldī)

masculinesingulara male given name from a Central Franconian form of Berhthold
Anno Dominieae incarnationis MVII, indictione V, Kalendis Novembris ... † Liudolfus Treverensis archiepiscopus interfui et subscripsi. † Berahtoldus Tollensis episcopus interfui et subscripsi. † Heimo Uuirdunensis episcopus interfui et subscripsi. ...(1007, Nov 1) ... † Liudolf, Archbishop of Trier, was present and undersigned. † Berahtold Bishop of Toule was present and undersigned. † Heimo, Bishop of Verdun, was present and undersigned. ...1900, Die Urkunden der deutschen Könige und Kaiser (Monumenta Germaniae Historica), Dritter Band. Die Urkunden Heinrichs II. und Arduins., Hannover: Hahnsche Buchhandlung, page 170:

Borrowed from Old High German Berhthold.