I'm not a great speller. I try to compensate by using spell check (which didn't see anything wrong with me writing about a seal used officially to give personal authority to a document in lieu of signature), the online Merriam Webster Dictionary, and other sources.
It was the other sources that led me astray on this one. I quickly Googled "swan signet" and got enough hits so I thought I had the spelling right.
Guess that just proves I'm not the only one who can't spell "cygnet". It also proves that just because I find a spelling in Google I can't assume it's correct.
I know I have many readers who must have winced when they saw "cygnet" spelled "signet".
Why didn't you gently tell me? It would have been kind.