To separate railings that are connected close together, I use P-B-L De-spruing nippers, part #804. They are like tweezers, but the end is a cross-wise blade, with a very fine point at one side. I got them in a model railroad store.
G, for those nibs, I have a set of very small scissors (Solingen Dovo 45) that came from one of the cutlery shops in the big shopping malls. I am usually pretty successful in holding those close along the side of the railings, and snipping and re-snipping until I can't feel the nib with my fingertip anymore. (Note, the scissors were not from any kind of a sewing/craft store - those have not been as good for me)
Rick