I think that some more information is required here. Judges don't decide upon issues of guilt. If the case was heard before a magistrates' court, the decision would be made by the magistrates. If the case was heard in the Crown Court, it's the jury who determine guilt. So we need to know whether you appeared in a magistrates' court or the Crown Court.
Next, we need to know what you were actually charged with. As far as I can see from the CPS website, there's not a specific charge of 'assault with an offensive weapon'. Your post could refer to a very minor case of common assault, under Section 9 of the Criminal Justice Act, where the 'offensive weapon' was nothing more than a folded newspaper which you (allegedly) whacked someone's ear with.
Equally, it could refer to something as serious as a charge under Section 18 of the Offences Against the Person Act, where you (allegedly) attacked someone with a hammer, or a knife, which you'd (allegedly) carried specifically for the purpose.
In the former example, you'd get a 'slap on the wrist', such as a supervision order (possibly coupled with and order to attend an anger management course). You might even get nothing more than a conditional discharge.
In the latter example, you'd probably be facing a prison sentence of between 1 and 5 years. Please tell us exactly what you've been convicted of (irrespective of whether you actually did it), and in which court, and we'll try to give you an indication of the likely sentence.
Chris