I'm thinking that, as the peacemaker, it might have been even wiser for you to try to encourage the older gentleman to simply retreat, even if he was in the right. While a situation like this is frustrating, it isn't worth coming to blows - especially in a church.
And for what it's worth, the Bible gives direction for situations like this in Matthew 18, and those instructions don't include coming to a forum like this one regarding a internal problem that occurred in your church. 1 Cor. 6:5-7 has this to say about situations such as this one: "I say this to your shame. Can it be that there is no one among you wise enough to settle a dispute between the brothers, but brother goes to law against brother, and that before unbelievers? To have lawsuits at all with one another is already a defeat for you. Why not rather suffer wrong? Why not rather be defrauded?" Understanding that this is hardly a court of law, the principle still holds. Situations like this should be handled IN the church, BY the church, not aired for all the world to see. And my remarks should not be taken as saying that everyone on this forum is an unbeliever; simply that this forum is an incredibly inappropriate place to be coming for input about this situation.
I'm not even going to address the issue of whether it would have been right for you to draw your firearm. I suspect the situation could have been diffused if someone had had the humility to back off when the situation began to escalate - even if they were in the right.
"...God, has bestowed upon every one of us the right to defend his person, his liberty, and his property..." Frederic Bastiat, The Law, 1850. "...And let the one who has no sword sell his cloak and buy one." Jesus Christ, Luke 22:36