The 12 year old was implied to just be using their fists. I’ve said it before: weapons are the great equalizer. However, the right kind of weapon is important. Which is why I suggested Starke link The Iron Monkey clip because the teen martial artist (a girl who is masquerading as a boy for personal safety, a common trope) uses a staff. When it gets destroyed by another more powerful martial artist, the battle quickly goes against her.
It’s also film, so take it with a grain of salt.
The main takeaway should be that you cannot treat children in your stories like they are mini-adults and you need to recognize that they do not fight under the same rules. They are far more fragile. Combat is always chance and the more you stack the deck against a character, the less likely they are to walk away.
A 12 year old runs a significantly higher risk of being crippled for life, for example, simply by the virtue of fighting. Combat is a grueling two-way street. No matter how good you are, you will get hurt. The physics principle applies, “for every action, there is an equal and opposite reaction”, hit someone and you will take a portion of that force back into yourself. You will take damage from hitting someone, you can be hurt when hurting someone else.
It doesn’t matter how good you are. At some point, it’s just going to go sideways. This 12 year old can’t make any mistakes, their body cannot take the beating if they fail and they will fail eventually. Do enough and the tide will turn. Your enemies will come back or come for revenge. An adult can change the game in a way that a twelve year old can’t counter. An adult can buy a gun over the counter at Walmart and shoot them with it. An adult can buy a tazer. Older teens can gang up on them in groups and take a baseball bat or crowbar to their skull.
Unless the kid is constantly on moving around with their parents or guardian, they will acquire enemies. They are fighting adults, which means they are acquiring the kind of enemies who don’t have a problem brutalizing children. Who won’t treat them any differently because they are a child. Treat a child like an adult in your story and you take away the safety that being a child grants them. To take a quote from The Incredibles:
“Remember the bad guys on the shows you used to watch on Saturday mornings? Well, these guys aren’t like those guys. They won’t exercise restraint because you are children. They will kill you if they get the chance. Do not give them that chance.”
In the movie, it’s an incredibly sobering moment because as much excitement as being a superhero presents it comes with the realization that both Dash and Violet can be killed by the average mook. They can be killed. They can die. Just like that.
The movie is good at reminding its audience that violence is serious and being a child who chooses to engage doesn’t grant special privileges.
A twelve year old can carry a weapon and fight, but it’s worth remembering the people they’ll be fighting can carry weapons too. If it’s adults then more than likely they have better ones and they aren’t afraid to use them.