You could just edit the image with all the icons saved on it. There's
a really good program for that here.
I'm not totally sure on changing the icon being used, but I was thinking you could just stick the escape code in the "terms" tab of the database, like "\i[123]Attack"
...I see now that you found an answer that works for you already, but I thought this might be useful in the future, so just posting anyway
Edit: escape codes definitely don't work there (at least, not without a plugin); not sure why I was thinking they did.