This upon me can be argued whether the second part of the name stands namely for 'city'. What about the first part 'melchi' - îìëé then it makes mainly no doubt, for such a root M-L-K(H) is common for the majority of Semitic languages. Still the thing is that the second can be also interpreted as àåø - 'or' which literally means light. Hebrew word for 'king' is 'melech'/'melekh' - îìê, and 'my king' is formed by adding '-i' ending to the main word (melech). Thus, 'melchi'/'melkhi' + 'or' = melchior = îìëéàåø = 'my king is light'.
A famous (sort of) bearer of this name is the character of Melchior Gabor from the play/musical, Spring Awakening. Originally written by Frank Wedekind, but has more recently been adapted into a musical by Duncan Sheik and Steven Sater.
This name was common among the Schwenkfelder religious community which moved from Silesia to America in the early 18th century. It appears approximately a dozen times in the passenger logs of the ships which brought the immigrants over, and among the first few generations born in America as well.