Hi,
Ufitsy's found the best answer already.
I was only going to add, that the "yes/no" answer from a CRB check will depend on the kind of job you apply for.
If the job you apply for is, say, working in a bank, and you had a fraud conviction of any kind, the CRB check would probably (but not always) come back with a "This person is NOT okay for this job position."
If however, you apply to work in a large branch of an AV Home Cinema Shop, with a conviction for injury to another person, out of self defence, and the other person only got a bruise, then the CRB check would probably (but again, not alwsy) come back with a "This person IS okay for this job position.", because the conviction would probably not be detrimental to your potential new job.
In your case, it depends on the type of weapon, whether you were charged (under what rules), what punishment/fine you received, and where, when and how long ago the offence took place. It also depends on what vacancy you are applying for.
Hope that helps a little.
Pooch