It's from Warhammer 40k. There are a number of classifications for human-settled worlds that range from civilized over forge world to feral. Feral worlds are colonies where humans have regressed to a pre-steam age tech level. The Imperium takes tithes from said worlds anyway, most of the time in form of warriors and/or soldiers. That can lead to situations as depicted above where a bronze age warrior is placed in a futuristic army company.What's the joke? I don't get it.