Some writers trace the second bit ... So I guess the truth of it is that no one knows.

Good lead, Rev. Alimae.

I see "tatterdemalion" was Dictionary.com's "Word of the Day for Monday October 15, 2001"

Tatterdemalion derives from tatter + -demalion, of unknown origin, though perhaps from Old French maillon, "long clothes, swadding clothes" or Italian maglia, "undershirt."

http://snipurl.com/g4wl

This "demalion" root could serve as a good building block for some new words.

How about "hiphopdemalion" or "funkydemalion" or "trampydemalion" or "trendydemailon" or "glitterdemalion"?