Obi means heart in African, and Wan is as above stated to be a word for "dark" yet if used in terms of wax and wane, it is the loss of or the diminishing, which ties into the plot as Obi-Wan is seen to lose all he has come to love and know, his major importance to Luke, and his early death in the movie series indicates his name can be connected to this translation as he is diminished in heart after he leaves Anakin, sees Padme die, and is left in charge of his near brother's only children, making him a man with a darkened heart or a diminished heart, as love lost by definition is the diminishing of the heart.
Only after he is called upon by Luke, does he present himself as Old-Ben, yet asks Luke still to call him just "Ben", being "son" in Hebrew, which can be linked to Obi-Wan and his old master as a man who loses his father figure, he is the anti-Vader to the story, and goes through all that Anakin does. He even goes as far as being called Ben until he dies, afterwards in the following movie he calls Ben by "Obi-Wan" again, and Yoda also refers to him as Obi-Wan.
Yet after he returns as a force ghost, Luke calls him Ben again, almost as if to state his status and character in the story. Ben being the "old son" is kind and happy, while Obi-Wan is colder, and more diminished in heart, making that cold manner seem more permanent. I believe the name Obi-Wan was chosen directly for its meaning, for Obi-Wan is actually a main focus in these stories, Luke being a carbon copy of both Obi-Wan and Anakin combined, represents the later battle of good versus evil that had started between his father Anakin and his true godfather Obi-Wan, represents righteous good, while his father represents absolute evil, and Luke himself represents the union and pacification of both good and evil into life.
In truth, I believe most of the writing began around Obi-Wan, Anakin being a mere after thought could have been any support character, as Obi-Wan had predating history prior to his debut in Episode 4. Ken or Kenne comes from German, and means to know, or be acquainted with, so Kenobi or Kenne obi means "to know heart", so put it all together, and Obi-Wan Kenobi means: "to lose ones heart to know ones heart" and yeah its not an exact translation, but you never will get one, all languages are subject to slang, err, misinterpretation, or falsification, meaning 1000 years from now all we say might be jibberish as all language on the Earth will have intermingled and mixed whilest many others will die off, so that being said, I'd like to believe this is the true meaning of the name Obi-Wan Kenobi, as to its origin, well, go ask George Lucas.