No, a more effective weapon for her would have been just a tiny little bit of knowledge. A brief 15-minute lesson (honestly, maybe as little as 5 minutes) in how to do a basic disarm would have done it.
You are right, of course, but the issue is a bit more complicated than that.
Many situations lend themselves to fairly simple defensive moves. All that is necessary is that the person who needs to perform the moves to have the knowledge and training to recognize the situation for what it is, evaluate the threat, determine the proper course of action, perform the action effectively in a timely manner.
A slightly different situation would likely require a different defensive action. So how much training and practice would be necessary for the average individual to be in a defensive situation and to have the right skill set for the situation? There are a lot of potential situations and a variety of potential manners of resolution. Just how many times has the woman with the purse been in a situation where she needed to disarm a pistol toting gunman?
A person skilled in self defense will see the school board shooting as having a variety of fairly simple solutions to stop the threat for a person with the right skill set and tools. The problem is that many of the folks with the defensive skillsets to handle these situations aren't school board members and the few that may be, aren't necessarily school board members where violence has happened while they were serving.
While only one skill might have been needed by Ginger Littleton to disarm Clay Duke, she would have needed many more to handle whatever might happen in a given day...and that is just for self defense crises. Ginger also needs all sorts of other multitudes of skillsets to handle other potential crises as well.
To a professional, the disarm looks easy, and it probably would be.
Of course, a self defense professional might not be prepared to step up and to effectively handle the types of crisis Littleton has to handle as a school board member. Simple administrative decisions could and have been botched by folks who don't understand the basics of administration, though the answers look easy to someone in that field.