[@rocketrobie2]That is 5 success... On a messy critical.

Well, good news first: Steel knows Exactly what that note means. He knows, because his beast knows.

Bad news: The beast is furious. Steel is going to fly into a rage, his claws are going to come out, and he's going to use them to destroy his guitar. 

Worse news: One of his band members-a human-had been following him, for a practice session. They see him go beast mode. Sara isn't far enough away to not see it, too. As the neck of the guitar breaks in his hand, the neck of his band mate breaks in hers. By the time he finishes destroying the entire instrument, Sara is gone, and the band mate is dead on the floor.

[@rocketrobie2] Please mark one stain on your CS in the CS section.

However, Steel knows some stuff; For one, there's a new Prince in town. For two, he's a Ventrue. This note is him marking his territory, and stating that life in the state is about to change.
Moreover, though, he got to you through Sara. The new Prince was in the same room with her, and gave her an order that she followed. Steel knows that some vampires have the power to control the minds of others. If Sara brought Steel that envelope, she was probably under someone else's control when it happened. There's no reason the Prince should know who Steel is, unless Sara told them. If Sara told them about you, she likely told them Everything.
In other words: The Prince knows your secrets. The Prince very likely knows All your secrets, and he's just invited you for an audience.