I got 3 Legbar cockerels out of a straight run of chicks and one was really flighty, from the beginning. He was the prettiest one, and a hen favorite, so I kept trying to get him to chill out but nothing seemed to work. He wouldn't even come over to me for treats, like the other 2. What finally worked was picking him up off his roost, just after dark, when he was relaxed. There were a couple of times I needed to do this for practical reasons, e.g. move him to a different coop. But I noticed that the more I picked him up and put him back down, the less he was afraid. I could never catch him any other way than off the roost when he was half asleep, so I did it intentionally a few more times, grabbed him quickly, but gently, and then put him back down before adrenaline had a chance to kick in. Next thing I knew, he started coming up to me for treats and has been much better since then.
In general, I have noticed none of my cockerels like to be "petted" so I just make a point to pick them up, hold them steady through any squirming (so they know who is in charge), and then, once they're calm I put them back down. When I pick them up, I scoop them from underneath, with my non-dominant hand, and let their feet dangle on either side of my arm. I keep control over them with my dominant (right) hand on top of their wings, and hold the cockerel close against my body. Keeps them from being able to squirm or flap their way out of my hands and they seem to remain calmer this way.