Introducing the problem.
While testing the siege battles for one of my scenes, a crazy idea sparked in my head: What if I could make the AI actually use the arrow slits correctly, without having them hide behind something that could prevent them to shoot. I'm pretty sure that we all know this problem, especially when defending a castle or a town. There are always those archers or crossbowmen who simply refuse to get in position and shoot the attacking enemies. The truth is that the AI is not programmed is any special way to use the battlements, so that's pretty much why they're only marginally effective. TaleWorlds tried to compensate this issue by placing multiple defender points on one single location (i.e: two defender spawns on one tower), thus completely filling a certain area with ranged units. While this does work to some extent, you'll always have those guys chilling behind a wall piece of the battlement. My solution is pretty simple, and it only requires some adjustments in the scene editor.
Applying the solution.
Things you need to work with in order to apply the fix: AI meshes; AI limiters.
First off, let's take a tower. As you can see in the screenshot below, I placed some convenient AI barriers which cover the spots behind which the AI can hide, or get blocked. Afterwards, I edited the AI mesh according to the barrier placement. In this example, a V shaped barrier placement does the job pretty well. You can try other combinations, depending on the angle you want the AI to shoot from, like a П shaped barrier placement.
In this second example, I chose to do the same thing for the wall slits of a tower. Normally, the AI would hardly get in position, let alone shoot through these narrow spots, but this can be easily fixed.
I hope this helps the enthusiansts out here with their siege scenarios.