Siracil - The Key of Nobles
Many stories place the key's origin to that of the First Kingdom, as a gift to or commission of the first noble family of Avalos lending to its namesake. But a closer examination of the lore and what remains of the roster of the High Guard of the Kingdom indicates that there was a Knight Guardian of the moniker Nobles.
Many of her activities as a Guardian remain unclear - however, I've been able to piece together a few details. She was critical to the success of the Guard in their earliest days - as their primary recruiter, responsible for many of their members. She acted also as trainer and advisor to both the Triumvirate and regular officers. Nobles' story would eventually lead to the creation of this key. You see, the tales where she is mentioned are the only known instances we have that record the recruitment of one of the Watchmen.
The creation of her key, Siracil, is as unique as its provenance. The key was seemingly transmuted from her existing Guardian identification tag. Starlight silver is supposed to be immutable beyond its native properties. The evidence would suggest otherwise -the hammer of Tyshin and the ten pointed path of the Sephyrial, the composed symbol of the Guardians, is still present.
But, her tenure in the Watch was short lived. She fell burning from the sky to protect her former colleagues, the guardians, sacrificing whatever power or status she gained in quiet observance. The legend says that she could not make the decision on her own - obey her oath of honor, or commit to the rules of her new duties. An impossible choice, really. The Watchmen keys, however, are quite wise and noble themselves. Her key saved her from the choice. In doing so, it destroyed itself.
But artifacts this powerful are like dreams - as long as someone remembers them, they exist in some form. The key before you is somewhat smaller and varies in detail from the descriptions I was able to locate. I am however certain that it was, at some point, a Guardian identification tag and it is made from starlight silver. I cannot be sure the process or power involved, but from the remnants of the dying key, it would appear it was reforged - held alive by the blue crystal at the top (and itself foreign to the style).