How big are your pens? Are they big enough for you to walk in and move around with the bird? I've had a few get real human aggressive in small pens that I couldn't get in there with them. I moved them to big pens then would throw some food on the ground before I stepped in.(as a distraction so they aren't just thinking about me) Then spent a few days just hanging out in there with them for about 10 minutes at a time. I just squat down against the wall and sit still talking to them, never even reaching for them. After a few days I will then do the same routine but pick them up and hold em. Sometimes it helps to gently "pet" their ear feathers with your thumb and forefinger. Just gentle hands and soft voice. I think that sometimes people tend to only handle their stags to work on them. Dubbing, force feeding them a wormer tablet, trimming spurs, moving from pen to pen ect.. After a while they start to associate a man with less than fun treatment. Most of my birds are full of attitude and kick their wings at me, and make a lot of noise, even peck at me a little. But rarely ever try to put a shuffle on me. And calm right down once I pick them up. Most are perfectly relaxed perched on my hand.
In other cases they are just spiteful and end up as man-fighters. Usually, as soon as I can I replace them if they get that way.