Based on the facts you provided, which include no narrative of what the State will rely on, there is no basis to assess the inquiry other then to note that the weight discrepancy in and of itself is unlikely to convince a judge to dismiss the charge. Before you go to Court, consult with a TX lawyer about what did happen, and ask the lawyer to provide you with an analysis of the possible defenses and dispositions. If you did not commit the offense, you should enter a not guilty plea, but need to proceed with an understanding of what will occur and what you are facing. Good luck.
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To be convicted of a class c assault, the State must prove beyond a reasonable doubt that you either intentionally or knowingly threatened another with imminent bodily injury OR intentionally or knowingly caused physical contact with another when the person knew or should reasonably believe that the other will regard the contact as offensive or provocative. The State should have to provide witnesses to these acts. If the officer witnessed the threats or the offensive or provocative contact(s), then the State will not necessarily have to bring the victim to court to testify. If the officer did not witness these events, then the State would have to bring the witnesses (assuming you or your lawyer make the right objections) to testify at trial since hearsay is generally inadmissible.
(I don't know why the weight thing is an issue. You can't really force them to change this. This is not something that is a real issue at trial, but it might go to the lack of the officer's attention to detail.)
There can be a lot of pitfalls trying your own case to a jury, but it is your right. I'd suggest talking with a local criminal defense attorney before going to trial. Most do free consultations.
Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.