Yes, Violet can be a unisex name, although it is more commonly used for girls. It is rare for boys but not unheard of.
There is no recognized saint by the name of Saint Violet in Christian tradition. It's possible that you may be referring to a local or regional saint not widely known.
the name Violet is beautiful!
Violet Campbell's birth name is Violet Shelton.
Violet Philpott's birth name is Violet Yeomans.
Violet Heming's birth name is Hemming, Violet.
Violet Affleck's birth name is Violet Anne Affleck.
Violet Murphy's birth name is Jessica Boucher.
Violet Axzelle's birth name is Evelyn Violet Axzelle.
Violet Loraine's birth name is Violet Mary Tipton.
Violet Lane's birth name is Violet Marion Lane.
Violet Lowe's birth name is Violet Renee' Hardin.
Violet Knights's birth name is Violet May Neitz.