The symbols, they were Aons! The ones on the temple that they needed to press to 'find' the bands! I always wondered what the hell that was, and the only explanation is Aons! Kelsier has encountered Elantrains and through some means learned a bit of it. The way they're described is very reminiscent of Aons! The only thing that makes me hesitant is how Kelsier learned any Aons, but he was very keen about learning things about the Cosmere. Maybe he asked some worldhoppers? What do you all think?!