We must add a new member variable to our AgentBehaviour class called weight and preferably assign a default value—in this case, 1.0f. Besides this, we should refactor the Update function to incorporate weight as a parameter to the Agent class' SetSteering function. All in all, the new AgentBehaviour class should look something like this:

public class AgentBehaviour : MonoBehaviour
{
    public float weight = 1.0f;

    // ... the rest of the class

    public virtual void Update ()
    {
        agent.SetSteering(GetSteering(), weight);
   }
}

We just need to change the SetSteering agent function's signature and definition:

public void SetSteering (Steering steering, float weight)
{
    this.steering.linear += (weight * steering.linear);
    this.steering.angular += (weight * steering.angular);
}

The weights are used to amplify the steering behavior result, and they're added to the main steering structure.

The weights don't necessarily need to add up to 1.0f. The weight parameter is a reference for defining the relevance that the steering behavior will have among the other ones.

In this project, there is an example of avoiding walls, worked out using weighted blending.