Help with an interior railing

I have an interior second floor landing with a long straight railing. There is no side support and it is a little weak. I am afraid the little one is going to lean to hard on it.
I remember some older houses having a diagonal support off a little extension on a stair or the floor - sort of a baluster on an angle to the straight run. I don't know what it is called . I guess I could design one, but I don't want to redesign the wheel.
Can anyone point me to one, or explain how this should be constructed.


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