First off, the obvious one: Saint George is the patron saint of soldiers. If you’re in the army, especially cavalry or armored units, he’s your man (or, well, your saint). The whole “knight killing a dragon” thing is basically the ultimate resume for military protection.
He’s also the patron of knights—which makes sense, given the armor. But think about it: knights weren’t just warriors; they were supposed to be chivalrous. So George is also about courage mixed with a code of honor. That’s a pretty heavy job description.
Fun side note: England, Portugal, Georgia, and Catalonia all claim him as their patron. That’s a lot of flags for one guy. Talk about spreading yourself thin across Europe.