Look what I have found. Maybe you have long known this ,but it was knew to me ...at least the first meaning.
The boy's name Darcy d(a)-rcy, dar-cy, also used as girl's name Darcy, is of Irish and Gaelic origin, and its meaning is "dark". Also a Norman place name, "from Arcy". Literary: Jane Austen named the haughty hero of "Pride and Prejudice" "Mr. Darcy", with connotations of Norman aristocracy.
Wow, thank you for this bit of info, Malena. I love the connotations you mention: the reference to darkness (so appropriate!), the Irish/Gaelic/Norman possible origin... it opens a world of new fanfiction possibilities, doesn't it?