Horst was not that bad
A lot of people seem to really criticize Horst Janson's acting performance in this film, but I really do not understand why. Sure he was not amazing, but he was pretty solid, especially during the scene where he reassures Grost after the tavern fight, he really seems to care about his friend and the emotion does come through.
Admittedly Ian Hendry might have been a better Kronos; if his cameo is any benchmark to his skills then the guy must have been absolutely brilliant. I think that Robert Shaw would have been an excellent Kronos as well if he was availible. But Horst was alright, even if he had the weakest portrayal of the main cast.