Actually, people like Dieter seem to win fights because they do something that is unexpected, not because they are much stronger or better pugilists. Even relatively weak people can defend themselves (or at least avoid getting hit) if they are expecting violence. So, I'd say that given that such situations often arise, we need to be mentally and emotionally prepared (not necessarily armed) for a violent confrontation.
Look around to see where the potential for trouble is; look at but also beyond stereotypes, i.e. note that a group of rowdy Westerners may make trouble but don't get so fixated on them that you ignore other possible causes of trouble. Also note potential weapons, e.g. bottles, mugs, glasses, liquids, barstools, the metal bar for bringing the roller shutters down, etc. Finally, look for escape routes and / or places of refuge, e.g. another group of drinkers who might come to your aid if trouble starts.
Those things done, go ahead and enjoy yourself.