Psion , try to explain.
In Kde install theme and then install the icons, right?
When you install a e17theme, the theme already has its own icons.
When I make a theme, I also put icons for that theme.
To change the default icons of e17 theme, the icons should be on.
Main Menu > Preferences > Options Panel > Theme Icons , select theme icons and check the box at the bottom of the window , apply.
KDE applications are a different things to applications Enlightenment , to unify the icons simply select what I say on the top line.
Another question that I want to change the icons one by one from the applications of the Ibar.
If that's what you want I can give you the icons I use for the Ibar.