As I understand it, Modulus, started by Greg Gould, I believe his name was, pioneered the use of carbon fiber to manufacture guitar and bass necks. He was friendly with the folks at Alembic and worked in conjunciton with them. The Blacknife guitar was made by Modulus under an agreement with Alembic that allowed use of the name. Bob Weir used to play one. Here's a link with more info on Weir's instrument:
http://dozin.com/bobs/guitars/index.htm There are others around here that are more familiar with the Modulus story, I believe David Fung knows a bit about these. I suspect someone will check in with more info. The neck is legit, and while private listings on eBay usually scare me off, I'd think if this was a scam, the seller would at least pretend the neck was in much better shape.
Bill, tgo