Possible translation error: The second part of Paracelsus' motto is given as "Media ad finem justificat" which Arty and Myka translate as "The end justifies the means". Google translate renders that phrase as "The means justifies the end". The same source translates "The end justifies the means" as "finis justificat modo".
While it is unclear by watching the scene how Pete was able to bronze Paracelsus as he had revealed in the previous episode that he was impervious to the bronzing process by having ingest certain chemicals, it is revealed in deleted scene that Pete using the scalpel on Paracelsus removed the anti-bronzing chemicals he had ingested, thus allowing him to be bronzed.