How long have you had him and when he "pinches" you, what are you doing? Does he tend to do it more at certain times than others? He's old enough to know how hard he is biting, but did he do it a lot as a baby too (just maybe lighter?)-- I am trying to picture what you are describing--- is it a bite? A video might help.
If he's doing it on purpose and you guys have a trusting relationship, you need to look at your behavior right BEFORE and right after the pinching occurs.
It could be that he is scared or nervous and that you aren't catching his body language (as adult birds in the wild rarely bite others--- and even then, only as a last resort).
.
He's also sexually mature at this age, so you are dealing with hormones that wouldn't have been present in a bird under 3 months-- They generally hit sexual maturity around 6 months, although that can vary.
If he has any huts, tents or access to shadowy spaces, remove them and prevent access (if you take stuff out of his cage, do it when he's not looking). Don't let him under furniture, in drawers, under blankets/pillows, in piles of paper, boxes etc.
Also, how is his diet and how much sleep is he getting nightly? They need 10 hours sleep on a schedule to regulate mood, immune health etc because light cycles and sleep tie to hormones, which overflow into all of these other areas.
