I just followed the link above and answered this, thinking it was today's blog post! I am only now realizing it is one year old.
I suppose my signature right now is cardigans, but I am more apt to go through phases and jags, where I will adopt a single "signature" item" and wear it daily for weeks on end, until moving on to the next item. For example, lately I've been sporting the yellow banana bag as a signature item, and also wearing a lot of grey plus white.
Thinking back over my lifetime, I remember in the late 80s/early 90s wearing a vintage pin on my lapel day after day. I OD'd on that look, but I saved those pins all these years, and have been enjoying wearing them again, in a new way.
Likewise I have a long onyx and gold necklace that was once a signature piece. I still have it but haven't worn it in eons. Perhaps I will again decide to go on a jag with it.
I went through a long period wearing red all the time. Nowadays, other than red shoes, I hesitate to wear red because I wore too much of it in that past phase.
And I had a green phase in recent years too. I still love green - and lately I feel a citron phase coming on.
Last summer I wore my long pearl necklace day after day.
You get the picture! I will fall in love with something, and want to wear it every day trying out new ways to make it fresh, until I get bored and I'm ready for the next new thing.