I have the same frustration as this person from 2006:
http://forums.esri.com/Thread.asp?c=93&f=1730&t=179255Why in the world are we not able to make the outlines of the character marker symbols (like "octagon 2", for example) thicker? The outline of all of those symbols is way too thin and there's no easy way to make them thicker.
My work around- add another symbol that's solid black beneath it and work to get the sizes right so it looks like a thicker outline. But this doesn't always look good.
A simple add would be a Use outline check box and a set thickness number dropdown, just like when you are using a "simple marker symbol". Can this be added?