Inspired by the growing international competition at the top level of the climbing world, Arnold managed to reach the difficulty of Xa in 1982 and Xb in 1983.

His first ascents of Barometer für Stimmungen at Heringstein and Garten Eden at Rokokoturm, both Xc, marked the climax of his rock-climbing career in 1986.

During the Cold War era, he was only in a few exceptional cases allowed to pursue climbing and mountaineering outside the Eastern Bloc.

Nevertheless, he became close friends with West German climbers Kurt Albert and Wolfgang Güllich, who visited Saxon Switzerland in the early 1980s and managed to repeat some of Arnold's hardest routes.

Arnold remains an active climber today and is a proponent of reforming the very strict traditional climbing regulations of the Saxon Switzerland area.