Was it wrong for teaching my brother self defense?

Knowing "self-defense" techniques and having the discretion to know when to use them are two different things.  In theory, he could have legally slapped her when she continued her attack after the first parry.  In reality, you're only allowed to use the MINIMUM for "reasonable and necessary" to stop the attack, which would have included stepping back and yelling at her.

You can't just "uppercut" someone who isn't going to actually harm you, but you do NOT have to wait for an attacker to land the first punch that could knock you out!

Let's hear the rest of the story.  I'm sure it's quite entertaining.

it mightve been better not to teach him that

He was arrested and fined and you question whether giving a woman a uppercut is "wrong?"  Yes, it was wrong.  I've read your other questions, and if you are arrested your mental impairment is NOT going to be an adequate defense.

it depends.... who is the woman? is she a criminal or a hooker or a street hustler or a bank robber?   

I call this "self defense".....   I also practice "taekwondo".....

This is a tricky one, i wouldn't worry too much about it but i would really like to know the full context from your brother's perspective as to what actually happened that day to give a justified answer. I don't think you are wrong to teach your brother self defence considering it is really important to learn how to protect yourself these days. How long was he arrested for? How hefty was the fine?  

Wrong. If she tried to hit him, he should have walked away and call the police to file charges. He does not have the right to hit a woman even if she threw the first punch.