If you want to use the latest Font Awesome icons, you'll need to update your sites to use them. This is easy to do with just an extra line of code in your phplugins.php file. And I've got a post about doing just that over on my TTG-Tips site.
Here is the info I got from Fontawesoe Get started page:
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.6.1/css/font-awesome.min.css">
Seems tha t new version is 4.6.1.