In order to take advantage of bézier handles, it is key to understand how they work and why they move the way they do.
Moho adapts the bézier curves during the animation. This is one of the software's biggest strengths, it is at the core of its movement system and allows any drawing to bend smoothly without much effort.
Here, for example, the bone is moving this arm and you can see how the bézier curve automatically adapts its rotation to follow the bone's movement (and, over that, you can still animate the bezier handles by hand if you want):
Now, this means the same will happen with corners like this one below. If you move the point at the top (using bones or moving the point itself), the bézier handles related to that point will also move:
So if you need to have a sharp corner and curves next to it, but you don't want it to be 'adapted' to the movement, the best is, instead of extending the bézier handles from the corner, to keep the corner totally sharp and add some extra points to control that curvature at the sides
That way, you will be able to animate both the corner and the curved sides exactly in the way you want, without unexpected changes
Look at this example below. At the top, the shape is created using bézier handles coming from the points in the middle. At the bottom a similar shape is achieved with extra points instead.
You can see how the shape at the bottom remains more consistent when it's rotated by the bones
I hope this clarifies some concepts and help you to have more control over vectors.
