Complex sentence: He also devoted himself to preservation for the future and to carry out certain artwork conservation-restoration, which required good touch and a good insight into the artworks, which should be repaired and special skills were necessary for the practical application.
Split into simpler sentences: He also devoted himself to preservation for the future and to carry out certain artwork conservation-restoration. That required a good touch and a good insight into the artworks, which should be repaired, and special skills were necessary for the practical application.