Interesting, Widewing.
I've seen it translated as "Lord of Armies" or "Lord of the Host." (EDIT: Checked around a little, and found I remembered incorrectly. Adonai itself was a substitute for the unpronounceable name of God, YHWH -- since traditionally it was considered sinful to speak the Name itself. Not being quite so picky, Christians threw some vowels in and transliterated YHWH into Yehovah, or Jehovah. While I thought Adonai itself meant "Lord of Hosts," that term was "Adonai Sabaoth." That should fulfill our daily quota for trivia, I'd think.)
However, back to the player -- I don't think he planned any deep meaning here. On first bumping into Adonai in the MA I made a comment about the handle, but it turns out he thought it meant something completely different. As I recall, he didn't even have the originating language right, much less the meaning.