I love #54, (the idea, etc...) - wonder if the peacock quill could be more colorful on the feather ends- teals/turquoise/purple/etc. Also, I guess it really looks great in standard capital letters with a simple font- I don't guess you could work a script or handwriting font in for the word signature? Guessing that may look to cluttered, like too much going on?
I don't think #45 and #44 are quite recognizable/brand-able enough, and I think on #47 and #48 I don't like the multiple feathers that sort of get cut off around the edges.