What advice do you have for managing a situation where my soldier has been arrested following his involvement in a fight at a local bar?

If the bar was “off limits” designation by the local command, he can receive punishment under the UCMJ. On the civilian side of the house he gets an arrest record. A misdemeanor or felony conviction, first offense, generally a fine and/or probation. If he has a security clearance this could be grounds to revoking that clearance. As his supervisor you have the obligation to closely monitor his behavior patterns. At the minimum restrict him to the company area, coupled with extra details. Do not let him think you are going to let him “off”, and that it’ll all be forgotten. Then the question is, is he mature enough to drink, obviously not, if chooses to get involved in a bar fight. Professional counseling is another option to be included with any of the above.

Stand by him and give him advice the best way you can. If there are charges, let him face up to them and do what's right.
Suggest counseling and staying away from situations like that one.

Yell at the phase of civilian judge being it was done on civilian property. Got to pay damages and whatever the judge requires our community service depending on how much damage they did. I know I've been in plenty of bar fights when I was in the young man in the army. And yes you will probably get a article 15 usually extra duty.

I would FG him if you have to but I would assume with your support that the court would sweep it under the rug

Try to support him and talk on his behalf to the command not to separate him but remember depending on how the proceeding go sometimes the command won’t be able to do anything

I was charged a number of years ago for simple assault and firearm charges. I wasn't under General Orders at the time and it occurred while I was off duty. Here's what I did
Let my leadership know
let my units Security Officer know as I maintain a clearance, and self reporting is the soldiers responsibility
and I Lawyered TF up.
I wound up beating my charges so the army really didn't care at all.
but, Article 92 is grounds for separation.
If you believe in him then stand by him.

Although the case could be a little different, situation can be similar. I had a Soldier who popped on his piss test in AIT. When I got him in my section, he turned out to be an outstanding Soldier. I counseled him and all my other Joe's every month, as required to do. When his case arrived to arrived to our unit, we were in an MP unit, he had to stand before the Provost Marshall (Bn. Cdr), the CSM & Cdr asked for his counseling file, to prove he was an excellent Soldier. In which he was. It saved his butt and saved him from losing rank and half his pay. So, what I'm telling you is that, his counseling will help save this Soldiers rear-end, IF the Soldier regrets what he did and seeks counseling of his own. That'll be your support of him, the rest and future actions will be on him.

Not sure and why he couldn’t go to the bar.

However, the legal stuff needs to play out if there’s no prosecution or he beats it there’s nothing there.

As far as the direct order to not go. You can push that immediately.