Sounds like you're complicit in letting it get to this point. YDI to you and your older son.

I don't know how old your children are but you've got to talk to your older son about this habit. Also, I don't know what you mean by "pick on" but that surely doesn't justify knocking your brother out via slingshot. Especially if it's the same kind of slingshot supposedly used in the David and Goliath story. That thing has the power of a .45 calibre bullet if used properly. Talk to them both or it may get worse.

Good. That bully of a big brother learned the hard way. Now you must discipline him with words to curtail his bullying and make him apologize to his little bro. 2 lessons taught for the price of one beating is better than having your son grow up to be a cowardly piece of shit that likes to pick on people and possibly wind up alone or dead for his cowardly behavior. Tell him it's wrong to bully people and that as he gets older, the greater the repercussions are for bullying. Bullies ruin lives and cause people to develop mental disorders or cause people to kill themselves. He wouldn't want to get in trouble or have that done to him. Also, do not have the big bro seek retribution. He got what he deserved. As for the little brother, give him some credit for standing up for himself cause self-defense is encouraged but remind him not get too addicted to using violence as a means to settle a dispute. Only as a last resort should he use violence. Take it from me who was a victim of physical and verbal antagonism for many years. I've seen and experienced this type of nature many times. Happy parenting, OP

Tbh your kids and the family should probably seek some sort of therapy to help manage the trauma and extreme emotional outbursts. Play and art therapy is great for kids especially but can be beneficial to all ages if you choose to have some sessions with your kids. For adults specifically, Dialectical Behavioral Therapy (DBT) has been a life changer for me and many others. Best of luck to you and your family!

Just like in the original, it's still great to see the bully get his comeuppance! Hope your older son learned his lesson.

While your younger son would benefit from learning that concussions are bad and we should use proportional responses, I'm a little worried that your elder son's gotten to the point of moving his own brother to violence. You need to take the elder in hand, now, or it will get worse.

Sounds like the oldest is a bully and his little brother finally stood up for himself. Looks like your oldest got what he deserved. Maybe he'll be less of a jerk now and think twice about bullying his brother.

TDI for sending them to Bible school

The brother got what he deserved

And you just let him pick on his little brother when he's in a foul mood? And what kind of school are they going to where David and Goliath are a subject?