In reply to Removed UserGRUMPY MONKEY:
I did a fair share of marked stuff in Julian Alps in Slovenia and I never used a harness. Keep in mind that most cables were placed before WWII - long before any via ferrata sets even existed. Helmet, however, is a good idea on certain paths, so don't leave it at home. One thing you should be aware of - some marked paths, although equipped with cables, are quite exposed and a possible fall would be fatal. If a falling rock hits you there, it might be a good idea to wear a harness & a via ferrata set. I never did, but I was willing to take that risk.