The first part of this safety improvement project was rounding the corners of the ledge with a jigsaw. I didn't want to bruise myself again on the square corner. Anyway, I practiced using the jigsaw on some scrap wood before doing the real thing, which is advisable since "practice makes perfect." Then I sanded the edge to ensure that it was smooth. Then came the long process of applying sealant, letting it dry and repeating those steps with another layer of sealant and 4 layers of varnish for both the ledge and the banister. That completed the ledge, but I still needed to attach the banister for safety improvement number 2.
First I had to find the studs in the wall. I invested in a studfinder that finds the edge and the center of the stud. I marked where the stud centers are with pencil and then marked where the handrail bracket (left picture) and banister needed to be on each stud in order to get the correct angle of the banister. I used my power drill to make holes through the drywall and into the studs for the handrail bracket screws and installed the brackets:
Mom came to the rescue again and held the banister many times, including when I needed to mark the spots for drilling holes for the other part of the handrail banister. After drilling those holes, I recommend putting on the piece most of the way so that there is just enough space to put the banister into place before finishing screwing it in place... Using a screwdriver from above is much easier than below in my opinion.