Is there a karamah (miraculous gift) for treating sorcery, and is the karamah of this man who treats sorcery and performs actions resembling Sufi "darwishah" (ecstatic rituals) authentic, and is it permissible to go to him for treatment?

A karamah (divine favor/miracle) is a right bestowed by Allah upon some of His pious saints who are steadfast upon the Sunnah (definition). A jinn may exit the body of someone afflicted by possession or sorcery out of obedience to the one blessed with karamah. An example of this is what occurred with Imam Ahmad ibn Hanbal, who commanded a jinn to leave the concubine of al-Mutawakkil, and the jinn obeyed him because he was obedient to Allah, whereas it did not obey his student al-Marwadhi after his death.

This indicates that karamah is granted to those who are steadfast and does not require "dervish-like" practices or innovations. The condition of the man mentioned in the question, with his striking of "shish" and his "dervish-like" practices, indicates that he is not among the steadfast, and therefore it is unlikely that he would attain karamah. However, this does not prevent him from treating sorcery with legitimate ruqyah (definition). If it is confirmed by trustworthy individuals that he does not engage in sorcery or shirk (definition), then there is no harm in seeking his help for ruqyah, although going to the people of the Sunnah is preferable.