Getting bitten by a snake during feeding is not a fun experience. Unlike when snakes strike defensively, when they strike for food they tend to latch on and attempt to constrict. Feeding 'by hand' is a bad idea not for the pain it will cause you but the feeding problems it can cause with your snake. If it were to bite you, you would probably have to pull it off. This will cause the animal to become very stressed. A bad feeding event like that can also cause a ball python to loose interest in food and become a trouble feeder especially with younger ball pythons.