Patching and Plastering - Fixing outside corner (sand over spackle?)

Hi,

I have a horsehair plaster wall, where the exterior corner has been "fixed" and painted in the past, so that the edge (6 feet height of it) is not depth-uniform at the corner. (It looks like someone cut into the corner, and then put spackle down, but didn't make their spackling job very even, and then hand sanded and painted over. There are no breaks in the wall (it is painted "smooth" at the moment.)

I looked at the instructions here:
http://www.doityourself.com/stry/fixingcrumplecorners which deals with plasterboard. Since I have horsehair plaster, I am not tempted to follow those instructions -- it would be a mess, and at some point would need cement fixative and joint compound anyway.

Ideas I have considered:

1. Put down some MH Ready Patch and using a power sander to make it smooth.

2. Put down a thin layer of wood laminate over the surface, spackle, and smooth.

Thoughts? Other ideas welcome.

I have never owned a power sander -- there are different kinds (belt, orbit, square) and would appreciate thoughts on the right tool for this job. (I lean to orbit based on gut.)

Ok if I got you right, you have one outside corner that needs to be fixed? I would go to home depot, or wherever and get a piece of tape-on-corner bead and some all purpose mud. Put a generous amount of mud on the corner to be fixed. Then stick your piece of corner bead in the mud. Mash it in there a little. make sure it is nice and straight then wipe down the edges of the paper on the bead. Let that dry. Then finish the corner bead as usual.

I would add....... never use a power sander on joint compound or plaster - too big of a mess!!!

Thanks both -- I'll try that.