Personally, I'd like to see what I'm buying, however, there's almost always more than one way to do things. Tony, what about listing the knife using a stock photo from Gerber (with permission), so potential buyers can see what the knife should look like.
If you get no takers, then it's probably a good indication that people want to see the knife so you'll have to unwrap it. Also, if you do this, make sure you indicate in the description that the knife was only opened for photographic purposes.
Maybe you could include "Before & After" pictures with a stamp date so interested parties could see that the box was opened on the same day it was listed, thereby documenting the sequence of events.
"If there are no Dogs in Heaven, then when I die, I want to go where they went". Will Rogers