Unless your set on that iron railing, I would replace it with treated
lumber. You can attach the uprights to the side of the steps by drilling and
bolting then fabricating the railing as you go. You could also sink a couple
of treated 4X4's one at the front and one at the back and use these as you
uprights. Then once you have your handrail up you can stain it as you like.
You could do this on both sides if you like and it would look great. As far
as the corner I wouldn't worry about it if you go with wood. But if you go
with the iron railing then I would just drill a new placement hole further
back from the corner. I have never been able to repair the corner and having
the repair NOT stand out, unless of course the steps are painted.

Hope that helps

Searcher