I know what you mean. The chick in my avatar was my special roo for a long time. He was the sweetest thing. Until he hit his teens... Overnight he turned into a nightmare. I couldn't walk across the yard without him attacking me. I'd stroke him and he'd be all loving and suddenly take a chunk out of my arm. He managed to get one of my hens stuck in the fence once and while I was trying to free her he started attacking me. You should've seen my arms after that drama. I kept slapping him and he kept coming back, biting and scratching me. I was a mess. I loved that roo so much, but that incident was the final straw. I rehomed him.
If you do a search here on you will find some threads on retraining aggressive roosters. Maybe there is something you can do to sort him out.