Oh, yeah, "Boku Renkin" (Armored Alchemist). This was very confusing when I first heard about Fullmetal Alchemist. Throw in the currently popular in the US series "Full Metal Panic" and you've got loads of confusion for a poor fangirl...
But like I said, I can't find even a scanlation. Or what it's about, or anything.
That can't make searching any easier! Sounds like alchemy is popular in anime.
Looks like you're right about Darth being a title:
Darth--Title taken by Sith Lords. Early Sith Lords did not carry this title as it had not been created yet, but then later Lords took the title as they saw fit. From Darth Bane onward, all Sith Lords took the title Darth. This is also the time when the tradition of one master one apprentice began.