Ja, I suppose a uniform might be a bit much. If you do make a symbol, make sure it's something simple, so it can be reproduced easily.

_{[Following another swig from his glass, he reaches into one of the inner pockets of his jacket, withdraws his wallet and pulls a business card out of it. Along with Leviathan's Claw's name and address, it bears the small, batlike symbol (http://i35.photobucket.com/albums/d168/Amberspike-Sama/LClawslogo.jpg) of the guild, which he points to as he slides the card across towards Zack.]}

Like that. Pretty simple, but distinct.

_{[Oh, another subject of interest.]} What are your meetings like?