I have one aggressive boy out of 6 roosters and 1 cockerel. I am keeping him for breeding (I know this goes contrary to most advice, but his offspring are all fairly gentle and sweet so far, and I think our relationship issues come from a little too much cuddling when he was a chick and I thought he was a really friendly pullet).
I just carry a red plastic shoehorn, it hangs by the door to his pen, and hold it out towards him when I’m in the pen with him. When I first started this I would tap him on the head with it firmly when he would attack and walk towards him. He no longer really tries to attack me, but waits until I’ve exited the pen then half heartedly “attacks” the corner of it next to the door. “See girls... I drove that big two leg predator that feeds us everyday away!” I always move towards him, never away, and make sure when I exit the pen it is on my terms, even if that means moving back in and walking him away from the door.
Move with confidence and wear jeans and long sleeves when handling them, yoga pants and tights are not appropriate for handing livestock (though I have emergency herded some cattle in summer pj bottoms and sandals!). Yes, they have sharp beaks, claws, and spurs, and put on a really good threat display, but this is maybe a 10lb animal when it comes down to it, don’t let him be in control of the situation. Would you be terrified of a cat, Pomeranian or chihuahua? Don’t be afraid of him, you can pick him up and tuck him under your arm. He might bite you, it will hurt a little, maybe even draw blood. But really he can’t do much damage to you if you’re properly clothed.
With kids around and attack behaviors I might make different choices. My Husband and I are the only people I will let handle my aggressive boy or enter his pen. Most of my boys are great though, so hopefully this doesn’t ruin the chicken keeping experience for you.