User blog comment:Yatanogarasu/What Did Blackbeard Do to Get the Gura Gura no Mi?/@comment-174.101.13.147-20110427072705

I think it was the absorption, and I also think the the cover draped over them wasn't to hide them, but to cover them in darkness which possibly made him stronger or allowed him to say absorb the power that was with him in the darkness.