This sounds like a case where the what would come out at trial is not what is in the offense report.... If there are witnesses that saw what happened that are not listed in the police report and their version of the facts is consistent with yours, then you should get them in touch with the prosecutor.
The attorney can certainly ask for an assault, but wether or not the state will offer it is another story.
This may be a case that needs to go to a trial if no one can agree on the facts.
Yes, the State could give him jail time and on an Aggravated Assault charge, he would do at least one-half of his sentence. However, with their lack of evidence of the gun and a witness recanting, the State would have an extremely difficult time proceeding on the deadly weapon portion of the charge. If the charge could be reduced to a Class A Misd., that would be a good result and he probably already has enough credit. Of course, it would be a conviction, so he may want to consider trying for a DADJ probation if offered. I am assuming your husband is a US Citizen. If not, the case is much more difficult due to the immigration consequences. It is still pretty early in the development of the case, but I would try to talk to the appointed attorney about getting the case resolved.
To see what the outcome is going to be, the case may need to be set for trial. If the State cannot find the complainant, they are likely to dismiss the case. Even having the witness, if the complainant is not interested in the case, then it is a waste of the court's time as well as the prosecutor's. However, the State does have the right to look for the guy which could take a while. 1 month is not that long of a time for the case to be pending. It could take a LOT longer than that.