Is it possible to use a Font Awesome icon as a favicon icon? You know, the little icon that appears along-side a website title in the browser tab?
Take a screenshot of something with the desired character, cut the part you want and save it as an image (.ico).
Seriously now, you may want to check the formats supported by each browser: http://en.wikipedia.org/wiki/Favicon#File_format_support
If your characters are image or vector files, you'll be ok with most browsers but IE (because MS hates you). Otherwise, well, you'll really have to save them as images first.