sometimes font awesome shows weird characters when you hit the page. Refreshing the page is one fix but sometimes it is not. You need to hard refresh to fix it.
I checked from developer console and I didn't see any errors. When I check the page css and fonts are loading correctly.
I'm using font awesome like this:
<i class="fa fa-hourglass-start fa-2x"></i>
or
<i class="fa fa-eye fa-2x"></i>
or
<i class="fa fa-ban"></i>