As you might have noticed, the editor doesn't allow duplicating content in cooked packages (as all of Epic's content is). This is because some of the source data has been repackaged or stripped out and performing these operations on some objects is unsafe. However, if you really want to try to copy that particle system or material so you can derive your own from it, there is something you can try.
NOTE: The editor doesn't normally allow this for a *reason*. Some object types won't work when you duplicate them this way, and you could crash the editor or corrupt data. Back up your mod packages before trying this or copy things into a new package until you're sure it works.
1. Open the log window. View -> Browser -> Log.
2. In the log console at the bottom, type:
the [package_to_save] is the name of the package you want to duplicate things out of, as seen in the Generic Browser. [filename] can be whatever you want - it won't be a valid file anyway and you should delete it when you're done. The purpose of saving is just to clear some things up that will allow duplication of most content to work.Code:obj savepackage file=[filename] package=[package_to_save]
3. Now, look at the package in the Generic Browser. All of the right click options (Duplicate, etc) should now be available. Duplicate the things you want into another package.
In general, objects that don't actually contain any mesh, texture, or sound data of their own will copy fine (Particle systems, materials, etc) while those that do won't save or load correctly. There really isn't any reason to duplicate those "base" types anyway.