Were I to go into farming tomorrow, I think I'd be paying somebody else to do the work around bulls!It is generally accepted by farmers that keeping a bull is not for everyone. The alternatives are to keep only bullocks for fattening, keep heifers for fattening (in which case there can be problems with neighbours bulls breaking out). Use artificial Insemination (not easy to detect heat and not easy to get the cows into the yard for service). Then there is keeping a bull.
The problem is that you never know when a bull can turn on you, he might be grand 99% of the time and change suddenly. I have never been attacked by a bull, but I have been attacked by cows immediately after calving when calves should be sprayed on the navel with disinfectant. .
The best weapon is a tabular steel bar with a welded grip handle and a clasp to attach a wrist leather band. You have to show you are determined to hit him/her hard of the head and actually hit them a light blow on the head. They wont come at you if they know you are going to hit them hard. The biggest problem is loosing the weapon during an attack and the strap prevents that happening.