As someone in the business, it is awesome to see folks discussing what we talk about in the courthouse all the time. It really is not complicated at all. Burnet County has a split jurisdiction with a County Attorney and a District Attorney. D.A. handle felonies for a number of counties in that judicial district. C.A. handles misdemeanors. I do think you could make a valid argument that the "spearing" caused the helmet to be used in a manner capable of causing serious bodily injury. This would then make this a felony aggravated assault. Not the easiest road but one that you could professionally support. They decided to go misdemeanor which is within their local discretion. The Penal Code Sec 7.02 is the basis for the charge as a "Party" which is if anyone ..."with the intent to promote or assist the commission of the offense a person solicits, encourages, directs, aids or attempts to aid the other person in committing the offense". We use this quite regularly in multiple defendant cases or when like I regularly do when I try gang cases. Just have to "direct or aid" and you are just as guilty. Like a recent gang head I tried for ordering a robbery that went bad when one of the crooks killed one of the other crooks while "sweeping" the house they had invaded. Used transferred intent and the law of parties and the head of the gang who never left their "clubhouse" is now serving life without parole. So they got the coach in effect for using his leadership position to "order" or encourage the act and thus making him criminally culpable. (Just a note as well, felony murder is when you commit, or attempt to commit, a felony and then commit an act dangerous to human life that causes the death of a another. My most recent one really drunk guy pulled a gun on his common-law Brother in Law and then had the gun go off during a struggle. Just changes what we have to prove from an intent struggle. This guy is serving a life sentence as well but can get out when he gets to his early 90s. )