About the current "pentagram" symbol:

However, its design is a little too complex to be used at small sizes, as you would in text or in a button. It’s also only available in image form, not as a typographical character.

We've used it as a tiny icon below posts from other instances and I've never found it problematic. I think it's already too well established to replace just because we can't type it. Besides, the three stars feel to me not distinct enough. Pushing Unicode Consortium to add it to the standard when the time comes is a batter way.

I do think however that it would be worth coming up with a proper name for the current symbol.